640707468840 has 72 divisors (see below), whose sum is σ = 2082348633690. Its totient is φ = 170851275072.

The previous prime is 640707468811. The next prime is 640707468883. The reversal of 640707468840 is 48864707046.

It can be written as a sum of positive squares in only one way, i.e., 576636721956 + 64070746884 = 759366^2 + 253122^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 15166227 + ... + 15208413.

Almost surely, 2^640707468840 is an apocalyptic number.

640707468840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

640707468840 is an abundant number, since it is smaller than the sum of its proper divisors (1441641164850).

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

640707468840 is an frugal number, since it uses more digits than its factorization.

640707468840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84391 (or 42197 counting only the distinct ones).

The product of its (nonzero) digits is 7225344, while the sum is 54.

The spelling of 640707468840 in words is "six hundred forty billion, seven hundred seven million, four hundred sixty-eight thousand, eight hundred forty".