644342231 has 16 divisors (see below), whose sum is σ = 731619840. Its totient is φ = 562554720.

The previous prime is 644342227. The next prime is 644342243. The reversal of 644342231 is 132243446.

It is not a de Polignac number, because 644342231 - 2² = 644342227 is a prime.

It is a super-2 number, since 2×644342231² = 830353821300114722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644342194 and 644342203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644342201) 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, 181766 + ... + 185276.

It is an arithmetic number, because the mean of its divisors is an integer number (45726240).

Almost surely, 2^644342231 is an apocalyptic number.

644342231 is a deficient number, since it is larger than the sum of its proper divisors (87277609).

644342231 is a wasteful number, since it uses less digits than its factorization.

644342231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4286.

The product of its digits is 13824, while the sum is 29.

The square root of 644342231 is about 25383.8970806297. The cubic root of 644342231 is about 863.7184542001.

Adding to 644342231 its reverse (132243446), we get a palindrome (776585677).

The spelling of 644342231 in words is "six hundred forty-four million, three hundred forty-two thousand, two hundred thirty-one".