644269376 has 56 divisors (see below), whose sum is σ = 1338437760. Its totient is φ = 307118592.

The previous prime is 644269361. The next prime is 644269393. The reversal of 644269376 is 673962446.

It is a self number, because there is not a number n which added to its sum of digits gives 644269376.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 645710 + ... + 646706.

Almost surely, 2^644269376 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644269376, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (669218880).

644269376 is an abundant number, since it is smaller than the sum of its proper divisors (694168384).

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

644269376 is a wasteful number, since it uses less digits than its factorization.

644269376 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1471 (or 1461 counting only the distinct ones).

The product of its digits is 1306368, while the sum is 47.

The square root of 644269376 is about 25382.4619767272. The cubic root of 644269376 is about 863.6858997713.

The spelling of 644269376 in words is "six hundred forty-four million, two hundred sixty-nine thousand, three hundred seventy-six".