644319 has 12 divisors (see below), whose sum is σ = 1002456. Its totient is φ = 396432.

The previous prime is 644297. The next prime is 644327. The reversal of 644319 is 913446.

644319 is a `hidden beast` number, since 644 + 3 + 19 = 666.

It is not a de Polignac number, because 644319 - 2⁷ = 644191 is a prime.

It is a super-2 number, since 2×644319² = 830293947522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 644292 and 644301.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644359) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2637 + ... + 2870.

It is an arithmetic number, because the mean of its divisors is an integer number (83538).

2⁶⁴⁴³¹⁹ is an apocalyptic number.

644319 is a deficient number, since it is larger than the sum of its proper divisors (358137).

644319 is a wasteful number, since it uses less digits than its factorization.

644319 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5526 (or 5523 counting only the distinct ones).

The product of its digits is 2592, while the sum is 27.

The square root of 644319 is about 802.6948361613. The cubic root of 644319 is about 86.3708073958.

The spelling of 644319 in words is "six hundred forty-four thousand, three hundred nineteen".