640535780 has 24 divisors (see below), whose sum is σ = 1347789240. Its totient is φ = 255706880.

The previous prime is 640535773. The next prime is 640535821. The reversal of 640535780 is 87535046.

640535780 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 168169024 + 472366756 = 12968^2 + 21734^2 .

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, 21281 + ... + 41640.

It is an arithmetic number, because the mean of its divisors is an integer number (56157885).

Almost surely, 2^640535780 is an apocalyptic number.

It is an amenable number.

640535780 is an abundant number, since it is smaller than the sum of its proper divisors (707253460).

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

640535780 is a wasteful number, since it uses less digits than its factorization.

640535780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63439 (or 63437 counting only the distinct ones).

The product of its (nonzero) digits is 100800, while the sum is 38.

The square root of 640535780 is about 25308.8083480831. The cubic root of 640535780 is about 862.0142887330.

The spelling of 640535780 in words is "six hundred forty million, five hundred thirty-five thousand, seven hundred eighty".