644279438 has 32 divisors (see below), whose sum is σ = 1077439968. Its totient is φ = 286473600.

The previous prime is 644279423. The next prime is 644279443. The reversal of 644279438 is 834972446.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 644279392 and 644279401.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 263156 + ... + 265592.

It is an arithmetic number, because the mean of its divisors is an integer number (33669999).

Almost surely, 2^644279438 is an apocalyptic number.

644279438 is a deficient number, since it is larger than the sum of its proper divisors (433160530).

644279438 is a wasteful number, since it uses less digits than its factorization.

644279438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2708.

The product of its digits is 1161216, while the sum is 47.

The square root of 644279438 is about 25382.6601836766. The cubic root of 644279438 is about 863.6903960077.

It can be divided in two parts, 644 and 279438, that added together give a palindrome (280082).

The spelling of 644279438 in words is "six hundred forty-four million, two hundred seventy-nine thousand, four hundred thirty-eight".