640402475 has 12 divisors (see below), whose sum is σ = 815562384. Its totient is φ = 498474720.

The previous prime is 640402471. The next prime is 640402481. The reversal of 640402475 is 574204046.

It is not a de Polignac number, because 640402475 - 2² = 640402471 is a prime.

It is a super-2 number, since 2×640402475² = 820230659972251250, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640402471) 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, 345239 + ... + 347088.

It is an arithmetic number, because the mean of its divisors is an integer number (67963532).

Almost surely, 2^640402475 is an apocalyptic number.

640402475 is a deficient number, since it is larger than the sum of its proper divisors (175159909).

640402475 is a wasteful number, since it uses less digits than its factorization.

640402475 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 692374 (or 692369 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 32.

The square root of 640402475 is about 25306.1746417747. The cubic root of 640402475 is about 861.9544852629.

The spelling of 640402475 in words is "six hundred forty million, four hundred two thousand, four hundred seventy-five".