664388007920 has 80 divisors (see below), whose sum is σ = 1901171858880. Its totient is φ = 210267850752.

The previous prime is 664388007917. The next prime is 664388008021. The reversal of 664388007920 is 29700883466.

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

It is a super-2 number, since 2×664388007920² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45623765 + ... + 45638324.

It is an arithmetic number, because the mean of its divisors is an integer number (23764648236).

Almost surely, 2^664388007920 is an apocalyptic number.

It is an amenable number.

664388007920 is an abundant number, since it is smaller than the sum of its proper divisors (1236783850960).

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

664388007920 is a wasteful number, since it uses less digits than its factorization.

664388007920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91262122 (or 91262116 counting only the distinct ones).

The product of its (nonzero) digits is 3483648, while the sum is 53.

The spelling of 664388007920 in words is "six hundred sixty-four billion, three hundred eighty-eight million, seven thousand, nine hundred twenty".