991475640 has 80 divisors (see below), whose sum is σ = 3332470680. Its totient is φ = 264392640.

The previous prime is 991475633. The next prime is 991475657. The reversal of 991475640 is 46574199.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 149766 + ... + 156245.

Almost surely, 2^991475640 is an apocalyptic number.

991475640 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

991475640 is an abundant number, since it is smaller than the sum of its proper divisors (2340995040).

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

991475640 is a wasteful number, since it uses less digits than its factorization.

991475640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306034 (or 306021 counting only the distinct ones).

The product of its (nonzero) digits is 272160, while the sum is 45.

The square root of 991475640 is about 31487.7061724096. The cubic root of 991475640 is about 997.1504343551.

The spelling of 991475640 in words is "nine hundred ninety-one million, four hundred seventy-five thousand, six hundred forty".