644911788096 has 63 divisors (see below), whose sum is σ = 1848578443933. Its totient is φ = 214964171520.

The previous prime is 644911788083. The next prime is 644911788097. The reversal of 644911788096 is 690887119446.

The square root of 644911788096 is 803064.

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

644911788096 is a `hidden beast` number, since 64 + 491 + 1 + 7 + 8 + 80 + 9 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 322469522496 + 322442265600 = 567864^2 + 567840^2 .

It is a super-2 number, since 2×644911788096² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644911788097) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 19256806 + ... + 19290266.

Almost surely, 2^644911788096 is an apocalyptic number.

644911788096 is the 803064-th square number.

It is an amenable number.

644911788096 is an abundant number, since it is smaller than the sum of its proper divisors (1203666655837).

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

644911788096 is an frugal number, since it uses more digits than its factorization.

644911788096 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66940 (or 33466 counting only the distinct ones).

The product of its (nonzero) digits is 20901888, while the sum is 63.

The spelling of 644911788096 in words is "six hundred forty-four billion, nine hundred eleven million, seven hundred eighty-eight thousand, ninety-six".