644138 has 32 divisors (see below), whose sum is σ = 1175040. Its totient is φ = 261360.

The previous prime is 644131. The next prime is 644141. The reversal of 644138 is 831446.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644138.

It is not an unprimeable number, because it can be changed into a prime (644131) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9581 + ... + 9647.

It is an arithmetic number, because the mean of its divisors is an integer number (36720).

2⁶⁴⁴¹³⁸ is an apocalyptic number.

644138 is a deficient number, since it is larger than the sum of its proper divisors (530902).

644138 is a wasteful number, since it uses less digits than its factorization.

644138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122.

The product of its digits is 2304, while the sum is 26.

The square root of 644138 is about 802.5820830295. The cubic root of 644138 is about 86.3627189695.

It can be divided in two parts, 6 and 44138, that added together give a palindrome (44144).

The spelling of 644138 in words is "six hundred forty-four thousand, one hundred thirty-eight".