640409732 has 12 divisors (see below), whose sum is σ = 1126979280. Its totient is φ = 318415656.

The previous prime is 640409713. The next prime is 640409741. The reversal of 640409732 is 237904046.

It is a junction number, because it is equal to n+sod(n) for n = 640409692 and 640409701.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 446498 + ... + 447929.

It is an arithmetic number, because the mean of its divisors is an integer number (93914940).

Almost surely, 2^640409732 is an apocalyptic number.

It is an amenable number.

640409732 is a deficient number, since it is larger than the sum of its proper divisors (486569548).

640409732 is a wasteful number, since it uses less digits than its factorization.

640409732 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 894610 (or 894608 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 35.

The square root of 640409732 is about 25306.3180253470. The cubic root of 640409732 is about 861.9577411216.

The spelling of 640409732 in words is "six hundred forty million, four hundred nine thousand, seven hundred thirty-two".