640990476 has 48 divisors (see below), whose sum is σ = 1899233280. Its totient is φ = 183139920.

The previous prime is 640990459. The next prime is 640990481. The reversal of 640990476 is 674099046.

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, 423180 + ... + 424691.

It is an arithmetic number, because the mean of its divisors is an integer number (39567360).

Almost surely, 2^640990476 is an apocalyptic number.

It is an amenable number.

640990476 is an abundant number, since it is smaller than the sum of its proper divisors (1258242804).

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

640990476 is a wasteful number, since it uses less digits than its factorization.

640990476 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 847891 (or 847883 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 45.

The square root of 640990476 is about 25317.7897139541. The cubic root of 640990476 is about 862.2182126732.

The spelling of 640990476 in words is "six hundred forty million, nine hundred ninety thousand, four hundred seventy-six".