644922432 has 448 divisors, whose sum is σ = 2446202880. Its totient is φ = 161740800.

The previous prime is 644922413. The next prime is 644922433. The reversal of 644922432 is 234229446.

644922432 is a `hidden beast` number, since 644 + 9 + 2 + 2 + 4 + 3 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (448).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644922433) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4923007 + ... + 4923137.

Almost surely, 2^644922432 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 644922432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1223101440).

644922432 is an abundant number, since it is smaller than the sum of its proper divisors (1801280448).

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

644922432 is a wasteful number, since it uses less digits than its factorization.

644922432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207 (or 191 counting only the distinct ones).

The product of its digits is 82944, while the sum is 36.

The square root of 644922432 is about 25395.3230339762. The cubic root of 644922432 is about 863.9776228772.

The spelling of 644922432 in words is "six hundred forty-four million, nine hundred twenty-two thousand, four hundred thirty-two".