991156520 has 16 divisors (see below), whose sum is σ = 2230102260. Its totient is φ = 396462592.

The previous prime is 991156513. The next prime is 991156541. The reversal of 991156520 is 25651199.

991156520 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 904926724 + 86229796 = 30082^2 + 9286^2 .

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, 12389417 + ... + 12389496.

Almost surely, 2^991156520 is an apocalyptic number.

It is an amenable number.

991156520 is an abundant number, since it is smaller than the sum of its proper divisors (1238945740).

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

991156520 is a wasteful number, since it uses less digits than its factorization.

991156520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24778924 (or 24778920 counting only the distinct ones).

The product of its (nonzero) digits is 24300, while the sum is 38.

The square root of 991156520 is about 31482.6383900714. The cubic root of 991156520 is about 997.0434407051.

The spelling of 991156520 in words is "nine hundred ninety-one million, one hundred fifty-six thousand, five hundred twenty".