644757472 has 48 divisors (see below), whose sum is σ = 1304245152. Its totient is φ = 313569280.

The previous prime is 644757439. The next prime is 644757511. The reversal of 644757472 is 274757446.

It is a super-3 number, since 3×644757472³ (a number of 27 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (46) coincides with the sum of the digits of its prime factors.

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, 659448 + ... + 660424.

It is an arithmetic number, because the mean of its divisors is an integer number (27171774).

Almost surely, 2^644757472 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 644757472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (652122576).

644757472 is an abundant number, since it is smaller than the sum of its proper divisors (659487680).

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

644757472 is a wasteful number, since it uses less digits than its factorization.

644757472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1531 (or 1523 counting only the distinct ones).

The product of its digits is 1317120, while the sum is 46.

The square root of 644757472 is about 25392.0749841363. The cubic root of 644757472 is about 863.9039530864.

The spelling of 644757472 in words is "six hundred forty-four million, seven hundred fifty-seven thousand, four hundred seventy-two".