• 396 can be written using four 4's:

See also 113.

• 396 is the smallest number that is made of nontrivial runs of identical digits in base 2 and 3. We have 396 = (110001100)₂ = (112200)₃.

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396 has 18 divisors (see below), whose sum is σ = 1092. Its totient is φ = 120.

The previous prime is 389. The next prime is 397. The reversal of 396 is 693.

Added to its reverse (693) it gives a square (1089 = 33²).

396 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nude number because it is divisible by every one of its digits.

It is one of the 548 Lynch-Bell numbers.

It is a plaindrome in base 13 and base 16.

It is a nialpdrome in base 11.

It is a zygodrome in base 2 and base 3.

It is not an unprimeable number, because it can be changed into a prime (397) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 31 + ... + 41.

396 is a gapful number since it is divisible by the number (36) formed by its first and last digit.

396 is the 11-th nonagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 396, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (546).

396 is an abundant number, since it is smaller than the sum of its proper divisors (696).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

396 is a wasteful number, since it uses less digits than its factorization.

396 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21 (or 16 counting only the distinct ones).

The product of its digits is 162, while the sum is 18.

The square root of 396 is about 19.8997487421. The cubic root of 396 is about 7.3434204620.

Adding to 396 its sum of digits (18), we get a palindrome (414).

Subtracting from 396 its sum of digits (18), we obtain a triangular number (378 = T₂₇).

396 divided by its sum of digits (18) gives a palindrome (22).

Adding to 396 its reverse (693), we get a square (1089 = 33²).

It can be divided in two parts, 39 and 6, that added together give a triangular number (45 = T₉).

The spelling of 396 in words is "three hundred ninety-six", and thus it is an aban number and an oban number.