991608864 has 48 divisors (see below), whose sum is σ = 2604625632. Its totient is φ = 330326528.

The previous prime is 991608851. The next prime is 991608887. The reversal of 991608864 is 468806199.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (48).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 250807 + ... + 254729.

It is an arithmetic number, because the mean of its divisors is an integer number (54263034).

Almost surely, 2^991608864 is an apocalyptic number.

It is an amenable number.

991608864 is an abundant number, since it is smaller than the sum of its proper divisors (1613016768).

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

991608864 is a wasteful number, since it uses less digits than its factorization.

991608864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6569 (or 6561 counting only the distinct ones).

The product of its (nonzero) digits is 746496, while the sum is 51.

The square root of 991608864 is about 31489.8215936515. The cubic root of 991608864 is about 997.1950945278.

The spelling of 991608864 in words is "nine hundred ninety-one million, six hundred eight thousand, eight hundred sixty-four".