640447132 has 18 divisors (see below), whose sum is σ = 1213629648. Its totient is φ = 295590672.

The previous prime is 640447127. The next prime is 640447133. The reversal of 640447132 is 231744046.

It is a junction number, because it is equal to n+sod(n) for n = 640447094 and 640447103.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640447133) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 473028 + ... + 474379.

Almost surely, 2^640447132 is an apocalyptic number.

It is an amenable number.

640447132 is a deficient number, since it is larger than the sum of its proper divisors (573182516).

640447132 is a wasteful number, since it uses less digits than its factorization.

640447132 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 947437 (or 947422 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 31.

The square root of 640447132 is about 25307.0569604607. The cubic root of 640447132 is about 861.9745202712.

The spelling of 640447132 in words is "six hundred forty million, four hundred forty-seven thousand, one hundred thirty-two".