644730131 has 2 divisors, whose sum is σ = 644730132. Its totient is φ = 644730130.

The previous prime is 644730113. The next prime is 644730137. The reversal of 644730131 is 131037446.

Together with previous prime (644730113) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644730131 is a prime.

It is a super-2 number, since 2×644730131² = 831353883638554322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 644730094 and 644730103.

It is not a weakly prime, because it can be changed into another prime (644730137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322365065 + 322365066.

It is an arithmetic number, because the mean of its divisors is an integer number (322365066).

Almost surely, 2^644730131 is an apocalyptic number.

644730131 is a deficient number, since it is larger than the sum of its proper divisors (1).

644730131 is an equidigital number, since it uses as much as digits as its factorization.

644730131 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6048, while the sum is 29.

The square root of 644730131 is about 25391.5366017892. The cubic root of 644730131 is about 863.8917416049.

Adding to 644730131 its reverse (131037446), we get a palindrome (775767577).

The spelling of 644730131 in words is "six hundred forty-four million, seven hundred thirty thousand, one hundred thirty-one".