664243920 has 60 divisors (see below), whose sum is σ = 2230754916. Its totient is φ = 177131520.

The previous prime is 664243897. The next prime is 664243939. The reversal of 664243920 is 29342466.

664243920 is a `hidden beast` number, since 6 + 642 + 4 + 3 + 9 + 2 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 513838224 + 150405696 = 22668^2 + 12264^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 460561 + ... + 462000.

Almost surely, 2^664243920 is an apocalyptic number.

664243920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

664243920 is an abundant number, since it is smaller than the sum of its proper divisors (1566510996).

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

664243920 is a wasteful number, since it uses less digits than its factorization.

664243920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 922580 (or 922571 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 36.

The square root of 664243920 is about 25772.9299847728. The cubic root of 664243920 is about 872.5209481483.

The spelling of 664243920 in words is "six hundred sixty-four million, two hundred forty-three thousand, nine hundred twenty".