991178680 has 32 divisors (see below), whose sum is σ = 2244371040. Its totient is φ = 393943680.

The previous prime is 991178677. The next prime is 991178687. The reversal of 991178680 is 86871199.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991178687) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 72636 + ... + 85195.

It is an arithmetic number, because the mean of its divisors is an integer number (70136595).

Almost surely, 2^991178680 is an apocalyptic number.

It is an amenable number.

991178680 is an abundant number, since it is smaller than the sum of its proper divisors (1253192360).

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

991178680 is a wasteful number, since it uses less digits than its factorization.

991178680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157999 (or 157995 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 49.

The square root of 991178680 is about 31482.9903281121. The cubic root of 991178680 is about 997.0508711891.

The spelling of 991178680 in words is "nine hundred ninety-one million, one hundred seventy-eight thousand, six hundred eighty".