644169239 has 12 divisors (see below), whose sum is σ = 758829600. Its totient is φ = 545152608.

The previous prime is 644169233. The next prime is 644169247. The reversal of 644169239 is 932961446.

It is a happy number.

It is not a de Polignac number, because 644169239 - 2²⁰ = 643120663 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644169239.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644169233) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 79334 + ... + 87075.

It is an arithmetic number, because the mean of its divisors is an integer number (63235800).

Almost surely, 2^644169239 is an apocalyptic number.

644169239 is a deficient number, since it is larger than the sum of its proper divisors (114660361).

644169239 is a wasteful number, since it uses less digits than its factorization.

644169239 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166502 (or 166495 counting only the distinct ones).

The product of its digits is 279936, while the sum is 44.

The square root of 644169239 is about 25380.4893372843. The cubic root of 644169239 is about 863.6411506858.

The spelling of 644169239 in words is "six hundred forty-four million, one hundred sixty-nine thousand, two hundred thirty-nine".