991688 has 16 divisors (see below), whose sum is σ = 1877580. Its totient is φ = 491008.

The previous prime is 991663. The next prime is 991693. The reversal of 991688 is 886199.

It can be written as a sum of positive squares in 2 ways, for example, as 813604 + 178084 = 902^2 + 422^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 356 + ... + 1452.

2⁹⁹¹⁶⁸⁸ is an apocalyptic number.

It is an amenable number.

991688 is a deficient number, since it is larger than the sum of its proper divisors (885892).

991688 is a wasteful number, since it uses less digits than its factorization.

991688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1216 (or 1212 counting only the distinct ones).

The product of its digits is 31104, while the sum is 41.

The square root of 991688 is about 995.8353277525. The cubic root of 991688 is about 99.7221621093.

The spelling of 991688 in words is "nine hundred ninety-one thousand, six hundred eighty-eight".