644682 has 16 divisors (see below), whose sum is σ = 1300320. Its totient is φ = 213072.

The previous prime is 644671. The next prime is 644687. The reversal of 644682 is 286446.

644682 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×644682² = 831229762248, which contains 22 as substring.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (644687) by changing a digit.

644682 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 7 ways as a sum of consecutive naturals, for example, 448 + ... + 1220.

It is an arithmetic number, because the mean of its divisors is an integer number (81270).

2⁶⁴⁴⁶⁸² is an apocalyptic number.

644682 is an abundant number, since it is smaller than the sum of its proper divisors (655638).

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

644682 is a wasteful number, since it uses less digits than its factorization.

644682 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 917.

The product of its digits is 9216, while the sum is 30.

The square root of 644682 is about 802.9209176501. The cubic root of 644682 is about 86.3870243717.

It can be divided in two parts, 644 and 682, that added together give a triangular number (1326 = T₅₁).

The spelling of 644682 in words is "six hundred forty-four thousand, six hundred eighty-two".