644036 has 6 divisors (see below), whose sum is σ = 1127070. Its totient is φ = 322016.

The previous prime is 644029. The next prime is 644047. The reversal of 644036 is 630446.

644036 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 348100 + 295936 = 590^2 + 544^2 .

It is a super-3 number, since 3×644036³ = 801404333975755968, which contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80501 + ... + 80508.

It is an arithmetic number, because the mean of its divisors is an integer number (187845).

2⁶⁴⁴⁰³⁶ is an apocalyptic number.

It is an amenable number.

644036 is a deficient number, since it is larger than the sum of its proper divisors (483034).

644036 is a wasteful number, since it uses less digits than its factorization.

644036 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161013 (or 161011 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 644036 is about 802.5185356115. The cubic root of 644036 is about 86.3581601833.

The spelling of 644036 in words is "six hundred forty-four thousand, thirty-six".