664704720 has 60 divisors (see below), whose sum is σ = 2232302436. Its totient is φ = 177254400.

The previous prime is 664704701. The next prime is 664704727. The reversal of 664704720 is 27407466.

664704720 is a `hidden beast` number, since 6 + 647 + 0 + 4 + 7 + 2 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 406909584 + 257795136 = 20172^2 + 16056^2 .

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

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664704727) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 460881 + ... + 462320.

Almost surely, 2^664704720 is an apocalyptic number.

664704720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

664704720 is an abundant number, since it is smaller than the sum of its proper divisors (1567597716).

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

664704720 is a wasteful number, since it uses less digits than its factorization.

664704720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 923220 (or 923211 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 36.

The square root of 664704720 is about 25781.8680471373. The cubic root of 664704720 is about 872.7226635647.

The spelling of 664704720 in words is "six hundred sixty-four million, seven hundred four thousand, seven hundred twenty".