644023174 has 4 divisors (see below), whose sum is σ = 966034764. Its totient is φ = 322011586.

The previous prime is 644023151. The next prime is 644023199. The reversal of 644023174 is 471320446.

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

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161005792 + ... + 161005795.

It is an arithmetic number, because the mean of its divisors is an integer number (241508691).

Almost surely, 2^644023174 is an apocalyptic number.

644023174 is a deficient number, since it is larger than the sum of its proper divisors (322011590).

644023174 is a wasteful number, since it uses less digits than its factorization.

644023174 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322011589.

The product of its (nonzero) digits is 16128, while the sum is 31.

The square root of 644023174 is about 25377.6116685554. The cubic root of 644023174 is about 863.5758690419.

It can be divided in two parts, 64402 and 3174, that added together give a palindrome (67576).

The spelling of 644023174 in words is "six hundred forty-four million, twenty-three thousand, one hundred seventy-four".