645711887844 has 81 divisors (see below), whose sum is σ = 1642900623273. Its totient is φ = 213837490944.

The previous prime is 645711887831. The next prime is 645711887869. The reversal of 645711887844 is 448788117546.

The square root of 645711887844 is 803562.

It is a perfect power (a square), and thus also a powerful number.

645711887844 is a `hidden beast` number, since 6 + 4 + 571 + 18 + 8 + 7 + 8 + 44 = 666.

It can be written as a sum of positive squares in only one way, i.e., 211314896100 + 434396991744 = 459690^2 + 659088^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 959452692 + ... + 959453364.

Almost surely, 2^645711887844 is an apocalyptic number.

645711887844 is the 803562-nd square number.

It is an amenable number.

645711887844 is an abundant number, since it is smaller than the sum of its proper divisors (997188735429).

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

645711887844 is an equidigital number, since it uses as much as digits as its factorization.

645711887844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1754 (or 877 counting only the distinct ones).

The product of its digits is 48168960, while the sum is 63.

The spelling of 645711887844 in words is "six hundred forty-five billion, seven hundred eleven million, eight hundred eighty-seven thousand, eight hundred forty-four".