644548231 has 2 divisors, whose sum is σ = 644548232. Its totient is φ = 644548230.

The previous prime is 644548189. The next prime is 644548237. The reversal of 644548231 is 132845446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644548231 - 2¹¹ = 644546183 is a prime.

It is a super-2 number, since 2×644548231² = 830884844170458722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644548237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322274115 + 322274116.

It is an arithmetic number, because the mean of its divisors is an integer number (322274116).

Almost surely, 2^644548231 is an apocalyptic number.

644548231 is a deficient number, since it is larger than the sum of its proper divisors (1).

644548231 is an equidigital number, since it uses as much as digits as its factorization.

644548231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 92160, while the sum is 37.

The square root of 644548231 is about 25387.9544469420. The cubic root of 644548231 is about 863.8104896822.

The spelling of 644548231 in words is "six hundred forty-four million, five hundred forty-eight thousand, two hundred thirty-one".