640500870 has 16 divisors (see below), whose sum is σ = 1537202160. Its totient is φ = 170800224.

The previous prime is 640500853. The next prime is 640500877. The reversal of 640500870 is 78005046.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30), and also a Moran number because the ratio is a prime number: 21350029 = 640500870 / (6 + 4 + 0 + 5 + 0 + 0 + 8 + 7 + 0).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640500877) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10674985 + ... + 10675044.

It is an arithmetic number, because the mean of its divisors is an integer number (96075135).

Almost surely, 2^640500870 is an apocalyptic number.

640500870 is an abundant number, since it is smaller than the sum of its proper divisors (896701290).

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

640500870 is a wasteful number, since it uses less digits than its factorization.

640500870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21350039.

The product of its (nonzero) digits is 6720, while the sum is 30.

The square root of 640500870 is about 25308.1186578536. The cubic root of 640500870 is about 861.9986281634.

The spelling of 640500870 in words is "six hundred forty million, five hundred thousand, eight hundred seventy".