644701236 has 72 divisors (see below), whose sum is σ = 1625035104. Its totient is φ = 198797760.

The previous prime is 644701177. The next prime is 644701237. The reversal of 644701236 is 632107446.

It is a happy number.

644701236 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 644701197 and 644701206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644701237) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 184546 + ... + 188006.

It is an arithmetic number, because the mean of its divisors is an integer number (22569932).

Almost surely, 2^644701236 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 644701236, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (812517552).

644701236 is an abundant number, since it is smaller than the sum of its proper divisors (980333868).

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

644701236 is a wasteful number, since it uses less digits than its factorization.

644701236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3549 (or 3528 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 33.

The square root of 644701236 is about 25390.9676066116. The cubic root of 644701236 is about 863.8788356755.

The spelling of 644701236 in words is "six hundred forty-four million, seven hundred one thousand, two hundred thirty-six".