644269231 has 2 divisors, whose sum is σ = 644269232. Its totient is φ = 644269230.

The previous prime is 644269217. The next prime is 644269273. The reversal of 644269231 is 132962446.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644269231 - 2⁷ = 644269103 is a prime.

It is a super-4 number, since 4×644269231⁴ (a number of 36 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644269201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322134615 + 322134616.

It is an arithmetic number, because the mean of its divisors is an integer number (322134616).

Almost surely, 2^644269231 is an apocalyptic number.

644269231 is a deficient number, since it is larger than the sum of its proper divisors (1).

644269231 is an equidigital number, since it uses as much as digits as its factorization.

644269231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62208, while the sum is 37.

The square root of 644269231 is about 25382.4591204241. The cubic root of 644269231 is about 863.6858349772.

The spelling of 644269231 in words is "six hundred forty-four million, two hundred sixty-nine thousand, two hundred thirty-one".