664730640 has 120 divisors (see below), whose sum is σ = 2551318848. Its totient is φ = 151937280.

The previous prime is 664730609. The next prime is 664730657. The reversal of 664730640 is 46037466.

664730640 is a `hidden beast` number, since 6 + 6 + 4 + 7 + 3 + 0 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (120).

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

It is a junction number, because it is equal to n+sod(n) for n = 664730595 and 664730604.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 60906 + ... + 70985.

Almost surely, 2^664730640 is an apocalyptic number.

664730640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

664730640 is an abundant number, since it is smaller than the sum of its proper divisors (1886588208).

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

664730640 is a wasteful number, since it uses less digits than its factorization.

664730640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 131917 (or 131908 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 36.

The square root of 664730640 is about 25782.3707210955. The cubic root of 664730640 is about 872.7340072870.

The spelling of 664730640 in words is "six hundred sixty-four million, seven hundred thirty thousand, six hundred forty".