644747333 has 2 divisors, whose sum is σ = 644747334. Its totient is φ = 644747332.

The previous prime is 644747309. The next prime is 644747351. The reversal of 644747333 is 333747446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 558944164 + 85803169 = 23642^2 + 9263^2 .

It is a cyclic number.

It is not a de Polignac number, because 644747333 - 2¹⁰ = 644746309 is a prime.

It is a super-2 number, since 2×644747333² = 831398246821225778, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644747303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322373666 + 322373667.

It is an arithmetic number, because the mean of its divisors is an integer number (322373667).

Almost surely, 2^644747333 is an apocalyptic number.

It is an amenable number.

644747333 is a deficient number, since it is larger than the sum of its proper divisors (1).

644747333 is an equidigital number, since it uses as much as digits as its factorization.

644747333 is an evil number, because the sum of its binary digits is even.

The product of its digits is 508032, while the sum is 41.

The square root of 644747333 is about 25391.8753344451. The cubic root of 644747333 is about 863.8994246819.

The spelling of 644747333 in words is "six hundred forty-four million, seven hundred forty-seven thousand, three hundred thirty-three".