640643635620406 has 32 divisors (see below), whose sum is σ = 1077450061082112. Its totient is φ = 283190548611360.

The previous prime is 640643635620349. The next prime is 640643635620431. The reversal of 640643635620406 is 604026536346046.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1973015956 + ... + 1973340631.

It is an arithmetic number, because the mean of its divisors is an integer number (33670314408816).

Almost surely, 2^{640643635620406} is an apocalyptic number.

640643635620406 is a deficient number, since it is larger than the sum of its proper divisors (436806425461706).

640643635620406 is a wasteful number, since it uses less digits than its factorization.

640643635620406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3946356804.

The product of its (nonzero) digits is 44789760, while the sum is 55.

The spelling of 640643635620406 in words is "six hundred forty trillion, six hundred forty-three billion, six hundred thirty-five million, six hundred twenty thousand, four hundred six".