991535664 has 40 divisors (see below), whose sum is σ = 2927392000. Its totient is φ = 283295808.

The previous prime is 991535647. The next prime is 991535707. The reversal of 991535664 is 466535199.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1475164 + ... + 1475835.

It is an arithmetic number, because the mean of its divisors is an integer number (73184800).

Almost surely, 2^991535664 is an apocalyptic number.

It is an amenable number.

991535664 is an abundant number, since it is smaller than the sum of its proper divisors (1935856336).

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

991535664 is a wasteful number, since it uses less digits than its factorization.

991535664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2951017 (or 2951011 counting only the distinct ones).

The product of its digits is 874800, while the sum is 48.

The square root of 991535664 is about 31488.6592918784. The cubic root of 991535664 is about 997.1705564666.

The spelling of 991535664 in words is "nine hundred ninety-one million, five hundred thirty-five thousand, six hundred sixty-four".