640513566 has 48 divisors (see below), whose sum is σ = 1730222208. Its totient is φ = 166366800.

The previous prime is 640513543. The next prime is 640513567. The reversal of 640513566 is 665315046.

640513566 is a `hidden beast` number, since 6 + 40 + 51 + 3 + 566 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 640513566.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640513567) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 229680 + ... + 232451.

It is an arithmetic number, because the mean of its divisors is an integer number (36046296).

Almost surely, 2^640513566 is an apocalyptic number.

640513566 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

640513566 is an abundant number, since it is smaller than the sum of its proper divisors (1089708642).

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

640513566 is a wasteful number, since it uses less digits than its factorization.

640513566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 462157 (or 462154 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 36.

The square root of 640513566 is about 25308.3694852118. The cubic root of 640513566 is about 862.0043236343.

The spelling of 640513566 in words is "six hundred forty million, five hundred thirteen thousand, five hundred sixty-six".