644356032 has 112 divisors (see below), whose sum is σ = 1847526912. Its totient is φ = 197406720.

The previous prime is 644356019. The next prime is 644356039. The reversal of 644356032 is 230653446.

It is a junction number, because it is equal to n+sod(n) for n = 644355984 and 644356002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644356039) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 138057 + ... + 142647.

It is an arithmetic number, because the mean of its divisors is an integer number (16495776).

Almost surely, 2^644356032 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 644356032, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (923763456).

644356032 is an abundant number, since it is smaller than the sum of its proper divisors (1203170880).

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

644356032 is a wasteful number, since it uses less digits than its factorization.

644356032 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4666 (or 4656 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 33.

The square root of 644356032 is about 25384.1689247452. The cubic root of 644356032 is about 863.7246207436.

The spelling of 644356032 in words is "six hundred forty-four million, three hundred fifty-six thousand, thirty-two".