645580659966 has 16 divisors (see below), whose sum is σ = 1408539621888. Its totient is φ = 195630503000.

The previous prime is 645580659961. The next prime is 645580659973. The reversal of 645580659966 is 669956085546.

It is a super-2 number, since 2×645580659966² (a number of 24 digits) contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 645580659966.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645580659961) 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, 4890762510 + ... + 4890762641.

It is an arithmetic number, because the mean of its divisors is an integer number (88033726368).

Almost surely, 2^645580659966 is an apocalyptic number.

645580659966 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

645580659966 is an abundant number, since it is smaller than the sum of its proper divisors (762958961922).

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

645580659966 is a wasteful number, since it uses less digits than its factorization.

645580659966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9781525167.

The product of its (nonzero) digits is 419904000, while the sum is 69.

The spelling of 645580659966 in words is "six hundred forty-five billion, five hundred eighty million, six hundred fifty-nine thousand, nine hundred sixty-six".