664405731 has 12 divisors (see below), whose sum is σ = 1046942520. Its totient is φ = 402670080.

The previous prime is 664405727. The next prime is 664405739. The reversal of 664405731 is 137504466.

It is a happy number.

664405731 is a `hidden beast` number, since 6 + 644 + 0 + 5 + 7 + 3 + 1 = 666.

664405731 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 664405731 - 2² = 664405727 is a prime.

It is a super-2 number, since 2×664405731² = 882869950771288722, which contains 22 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (664405739) 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, 3355486 + ... + 3355683.

It is an arithmetic number, because the mean of its divisors is an integer number (87245210).

Almost surely, 2^664405731 is an apocalyptic number.

664405731 is a deficient number, since it is larger than the sum of its proper divisors (382536789).

664405731 is a wasteful number, since it uses less digits than its factorization.

664405731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6711186 (or 6711183 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 36.

The square root of 664405731 is about 25776.0689594050. The cubic root of 664405731 is about 872.5917916142.

The spelling of 664405731 in words is "six hundred sixty-four million, four hundred five thousand, seven hundred thirty-one".