640637515 has 36 divisors (see below), whose sum is σ = 935038944. Its totient is φ = 420109536.

The previous prime is 640637509. The next prime is 640637539. The reversal of 640637515 is 515736046.

It is not a de Polignac number, because 640637515 - 2³ = 640637507 is a prime.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 127134 + ... + 132076.

It is an arithmetic number, because the mean of its divisors is an integer number (25973304).

Almost surely, 2^640637515 is an apocalyptic number.

640637515 is a deficient number, since it is larger than the sum of its proper divisors (294401429).

640637515 is a wasteful number, since it uses less digits than its factorization.

640637515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5008 (or 4978 counting only the distinct ones).

The product of its (nonzero) digits is 75600, while the sum is 37.

The square root of 640637515 is about 25310.8181416563. The cubic root of 640637515 is about 862.0599236447.

The spelling of 640637515 in words is "six hundred forty million, six hundred thirty-seven thousand, five hundred fifteen".