664807920 has 80 divisors (see below), whose sum is σ = 2355325440. Its totient is φ = 151955712.

The previous prime is 664807909. The next prime is 664807921. The reversal of 664807920 is 29708466.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664807921) 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 15 ways as a sum of consecutive naturals, for example, 196180 + ... + 199539.

It is an arithmetic number, because the mean of its divisors is an integer number (29441568).

Almost surely, 2^664807920 is an apocalyptic number.

664807920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

664807920 is an abundant number, since it is smaller than the sum of its proper divisors (1690517520).

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

664807920 is a wasteful number, since it uses less digits than its factorization.

664807920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 395742 (or 395736 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 42.

The square root of 664807920 is about 25783.8693760266. The cubic root of 664807920 is about 872.7678266351.

The spelling of 664807920 in words is "six hundred sixty-four million, eight hundred seven thousand, nine hundred twenty".