644505427 has 2 divisors, whose sum is σ = 644505428. Its totient is φ = 644505426.

The previous prime is 644505419. The next prime is 644505481. The reversal of 644505427 is 724505446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644505427 - 2³ = 644505419 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (644505487) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322252713 + 322252714.

It is an arithmetic number, because the mean of its divisors is an integer number (322252714).

Almost surely, 2^644505427 is an apocalyptic number.

644505427 is a deficient number, since it is larger than the sum of its proper divisors (1).

644505427 is an equidigital number, since it uses as much as digits as its factorization.

644505427 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 134400, while the sum is 37.

The square root of 644505427 is about 25387.1114347418. Note that the first 3 decimals coincide. The cubic root of 644505427 is about 863.7913675741.

The spelling of 644505427 in words is "six hundred forty-four million, five hundred five thousand, four hundred twenty-seven".