644638130231 has 4 divisors (see below), whose sum is σ = 646495877352. Its totient is φ = 642780383112.

The previous prime is 644638130219. The next prime is 644638130249. The reversal of 644638130231 is 132031836446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 132031836446 = 2 ⋅66015918223.

It is a cyclic number.

It is not a de Polignac number, because 644638130231 - 2¹⁰ = 644638129207 is a prime.

It is a super-2 number, since 2×644638130231² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644638180231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 928873040 + ... + 928873733.

It is an arithmetic number, because the mean of its divisors is an integer number (161623969338).

Almost surely, 2^644638130231 is an apocalyptic number.

644638130231 is a deficient number, since it is larger than the sum of its proper divisors (1857747121).

644638130231 is a wasteful number, since it uses less digits than its factorization.

644638130231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1857747120.

The product of its (nonzero) digits is 248832, while the sum is 41.

Adding to 644638130231 its reverse (132031836446), we get a palindrome (776669966677).

The spelling of 644638130231 in words is "six hundred forty-four billion, six hundred thirty-eight million, one hundred thirty thousand, two hundred thirty-one".