644216249 has 2 divisors, whose sum is σ = 644216250. Its totient is φ = 644216248.

The previous prime is 644216191. The next prime is 644216297. The reversal of 644216249 is 942612446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 628755625 + 15460624 = 25075^2 + 3932^2 .

It is a cyclic number.

It is not a de Polignac number, because 644216249 - 2²⁸ = 375780793 is a prime.

It is not a weakly prime, because it can be changed into another prime (644210249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322108124 + 322108125.

It is an arithmetic number, because the mean of its divisors is an integer number (322108125).

Almost surely, 2^644216249 is an apocalyptic number.

It is an amenable number.

644216249 is a deficient number, since it is larger than the sum of its proper divisors (1).

644216249 is an equidigital number, since it uses as much as digits as its factorization.

644216249 is an evil number, because the sum of its binary digits is even.

The product of its digits is 82944, while the sum is 38.

The square root of 644216249 is about 25381.4154254644. The cubic root of 644216249 is about 863.6621590277.

The spelling of 644216249 in words is "six hundred forty-four million, two hundred sixteen thousand, two hundred forty-nine".