991207664 has 20 divisors (see below), whose sum is σ = 1923678960. Its totient is φ = 494774400.

The previous prime is 991207631. The next prime is 991207669. The reversal of 991207664 is 466702199.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991207669) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 41924 + ... + 61155.

It is an arithmetic number, because the mean of its divisors is an integer number (96183948).

Almost surely, 2^991207664 is an apocalyptic number.

It is an amenable number.

991207664 is a deficient number, since it is larger than the sum of its proper divisors (932471296).

991207664 is a wasteful number, since it uses less digits than its factorization.

991207664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103688 (or 103682 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 44.

The square root of 991207664 is about 31483.4506368028. The cubic root of 991207664 is about 997.0605896659.

The spelling of 991207664 in words is "nine hundred ninety-one million, two hundred seven thousand, six hundred sixty-four".