644634 has 24 divisors (see below), whose sum is σ = 1422720. Its totient is φ = 210888.

The previous prime is 644629. The next prime is 644647. The reversal of 644634 is 436446.

It is a happy number.

644634 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 = 644598 and 644607.

It is an unprimeable number.

644634 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 759 + ... + 1365.

It is an arithmetic number, because the mean of its divisors is an integer number (59280).

2⁶⁴⁴⁶³⁴ is an apocalyptic number.

644634 is an abundant number, since it is smaller than the sum of its proper divisors (778086).

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

644634 is a wasteful number, since it uses less digits than its factorization.

644634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 674 (or 671 counting only the distinct ones).

The product of its digits is 6912, while the sum is 27.

The square root of 644634 is about 802.8910262296. The cubic root of 644634 is about 86.3848803275.

The spelling of 644634 in words is "six hundred forty-four thousand, six hundred thirty-four".