640565672 has 8 divisors (see below), whose sum is σ = 1201060650. Its totient is φ = 320282832.

The previous prime is 640565669. The next prime is 640565701. The reversal of 640565672 is 276565046.

It can be written as a sum of positive squares in only one way, i.e., 500237956 + 140327716 = 22366^2 + 11846^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-3 number, since 3×640565672³ (a number of 27 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40035347 + ... + 40035362.

Almost surely, 2^640565672 is an apocalyptic number.

It is an amenable number.

640565672 is a deficient number, since it is larger than the sum of its proper divisors (560494978).

640565672 is a wasteful number, since it uses less digits than its factorization.

640565672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80070715 (or 80070711 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 41.

The square root of 640565672 is about 25309.3988865797. The cubic root of 640565672 is about 862.0276977837.

The spelling of 640565672 in words is "six hundred forty million, five hundred sixty-five thousand, six hundred seventy-two".