644710373 has 4 divisors (see below), whose sum is σ = 645828300. Its totient is φ = 643592448.

The previous prime is 644710361. The next prime is 644710433. The reversal of 644710373 is 373017446.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 643028164 + 1682209 = 25358^2 + 1297^2 .

It is a cyclic number.

It is not a de Polignac number, because 644710373 - 2⁴ = 644710357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644710303) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 558098 + ... + 559251.

It is an arithmetic number, because the mean of its divisors is an integer number (161457075).

Almost surely, 2^644710373 is an apocalyptic number.

It is an amenable number.

644710373 is a deficient number, since it is larger than the sum of its proper divisors (1117927).

644710373 is a wasteful number, since it uses less digits than its factorization.

644710373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1117926.

The product of its (nonzero) digits is 42336, while the sum is 35.

The square root of 644710373 is about 25391.1475321617. The cubic root of 644710373 is about 863.8829167512.

The spelling of 644710373 in words is "six hundred forty-four million, seven hundred ten thousand, three hundred seventy-three".