640506394 has 16 divisors (see below), whose sum is σ = 1050809760. Its totient is φ = 290386960.

The previous prime is 640506367. The next prime is 640506401. The reversal of 640506394 is 493605046.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28864 + ... + 45979.

It is an arithmetic number, because the mean of its divisors is an integer number (65675610).

Almost surely, 2^640506394 is an apocalyptic number.

640506394 is a deficient number, since it is larger than the sum of its proper divisors (410303366).

640506394 is a wasteful number, since it uses less digits than its factorization.

640506394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75245.

The product of its (nonzero) digits is 77760, while the sum is 37.

The square root of 640506394 is about 25308.2277925579. The cubic root of 640506394 is about 862.0011062588.

The spelling of 640506394 in words is "six hundred forty million, five hundred six thousand, three hundred ninety-four".