644266739 has 2 divisors, whose sum is σ = 644266740. Its totient is φ = 644266738.

The previous prime is 644266699. The next prime is 644266759. The reversal of 644266739 is 937662446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644266739 - 2¹⁶ = 644201203 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 644266693 and 644266702.

It is not a weakly prime, because it can be changed into another prime (644266759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322133369 + 322133370.

It is an arithmetic number, because the mean of its divisors is an integer number (322133370).

Almost surely, 2^644266739 is an apocalyptic number.

644266739 is a deficient number, since it is larger than the sum of its proper divisors (1).

644266739 is an equidigital number, since it uses as much as digits as its factorization.

644266739 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1306368, while the sum is 47.

The square root of 644266739 is about 25382.4100313583. The cubic root of 644266739 is about 863.6847214118.

The spelling of 644266739 in words is "six hundred forty-four million, two hundred sixty-six thousand, seven hundred thirty-nine".