640309290 has 16 divisors (see below), whose sum is σ = 1536742368. Its totient is φ = 170749136.

The previous prime is 640309279. The next prime is 640309337. The reversal of 640309290 is 92903046.

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, 10671792 + ... + 10671851.

It is an arithmetic number, because the mean of its divisors is an integer number (96046398).

Almost surely, 2^640309290 is an apocalyptic number.

640309290 is an abundant number, since it is smaller than the sum of its proper divisors (896433078).

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

640309290 is a wasteful number, since it uses less digits than its factorization.

640309290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21343653.

The product of its (nonzero) digits is 11664, while the sum is 33.

The square root of 640309290 is about 25304.3334233487. Note that the first 3 decimals coincide. The cubic root of 640309290 is about 861.9126755531.

The spelling of 640309290 in words is "six hundred forty million, three hundred nine thousand, two hundred ninety".