644657577240 has 64 divisors (see below), whose sum is σ = 1978948857600. Its totient is φ = 167910809472.

The previous prime is 644657577233. The next prime is 644657577247. The reversal of 644657577240 is 42775756446.

It is an interprime number because it is at equal distance from previous prime (644657577233) and next prime (644657577247).

It is a hoax number, since the sum of its digits (57) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644657577247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62461660 + ... + 62471979.

It is an arithmetic number, because the mean of its divisors is an integer number (30921075900).

Almost surely, 2^644657577240 is an apocalyptic number.

644657577240 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644657577240 is an abundant number, since it is smaller than the sum of its proper divisors (1334291280360).

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

644657577240 is a wasteful number, since it uses less digits than its factorization.

644657577240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124933696 (or 124933692 counting only the distinct ones).

The product of its (nonzero) digits is 39513600, while the sum is 57.

The spelling of 644657577240 in words is "six hundred forty-four billion, six hundred fifty-seven million, five hundred seventy-seven thousand, two hundred forty".