640956834 has 32 divisors (see below), whose sum is σ = 1627827840. Its totient is φ = 183130416.

The previous prime is 640956803. The next prime is 640956851. The reversal of 640956834 is 438659046.

It is a self number, because there is not a number n which added to its sum of digits gives 640956834.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 847449 + ... + 848204.

It is an arithmetic number, because the mean of its divisors is an integer number (50869620).

Almost surely, 2^640956834 is an apocalyptic number.

640956834 is an abundant number, since it is smaller than the sum of its proper divisors (986871006).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640956834 is a wasteful number, since it uses less digits than its factorization.

640956834 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1695671 (or 1695665 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 45.

The square root of 640956834 is about 25317.1253107457. The cubic root of 640956834 is about 862.2031280744.

The spelling of 640956834 in words is "six hundred forty million, nine hundred fifty-six thousand, eight hundred thirty-four".