644023131 has 8 divisors (see below), whose sum is σ = 858841680. Its totient is φ = 429276672.

The previous prime is 644023033. The next prime is 644023151. The reversal of 644023131 is 131320446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 644023131 - 2¹¹ = 644021083 is a prime.

It is a super-2 number, since 2×644023131² = 829531586526086322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (644023151) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8331 + ... + 36843.

It is an arithmetic number, because the mean of its divisors is an integer number (107355210).

Almost surely, 2^644023131 is an apocalyptic number.

644023131 is a deficient number, since it is larger than the sum of its proper divisors (214818549).

644023131 is a wasteful number, since it uses less digits than its factorization.

644023131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36045.

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 644023131 is about 25377.6108213520. The cubic root of 644023131 is about 863.5758498223.

Adding to 644023131 its reverse (131320446), we get a palindrome (775343577).

The spelling of 644023131 in words is "six hundred forty-four million, twenty-three thousand, one hundred thirty-one".