640355915 has 16 divisors (see below), whose sum is σ = 814445280. Its totient is φ = 481666560.

The previous prime is 640355899. The next prime is 640355923. The reversal of 640355915 is 519553046.

It is not a de Polignac number, because 640355915 - 2⁴ = 640355899 is a prime.

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, 97196 + ... + 103574.

It is an arithmetic number, because the mean of its divisors is an integer number (50902830).

Almost surely, 2^640355915 is an apocalyptic number.

640355915 is a deficient number, since it is larger than the sum of its proper divisors (174089365).

640355915 is a wasteful number, since it uses less digits than its factorization.

640355915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7582.

The product of its (nonzero) digits is 81000, while the sum is 38.

The square root of 640355915 is about 25305.2546914668. The cubic root of 640355915 is about 861.9335954969.

The spelling of 640355915 in words is "six hundred forty million, three hundred fifty-five thousand, nine hundred fifteen".