640947506 has 16 divisors (see below), whose sum is σ = 1016644608. Its totient is φ = 302570400.

The previous prime is 640947479. The next prime is 640947521. The reversal of 640947506 is 605749046.

It is a Harshad number since it is a multiple of its sum of digits (41).

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, 123530 + ... + 128613.

It is an arithmetic number, because the mean of its divisors is an integer number (63540288).

Almost surely, 2^640947506 is an apocalyptic number.

640947506 is a deficient number, since it is larger than the sum of its proper divisors (375697102).

640947506 is a wasteful number, since it uses less digits than its factorization.

640947506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252217.

The product of its (nonzero) digits is 181440, while the sum is 41.

The square root of 640947506 is about 25316.9410869481. The cubic root of 640947506 is about 862.1989454371.

The spelling of 640947506 in words is "six hundred forty million, nine hundred forty-seven thousand, five hundred six".