644742677 has 2 divisors, whose sum is σ = 644742678. Its totient is φ = 644742676.

The previous prime is 644742661. The next prime is 644742719. The reversal of 644742677 is 776247446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 471714961 + 173027716 = 21719^2 + 13154^2 .

It is a cyclic number.

It is not a de Polignac number, because 644742677 - 2⁴ = 644742661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644742277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322371338 + 322371339.

It is an arithmetic number, because the mean of its divisors is an integer number (322371339).

Almost surely, 2^644742677 is an apocalyptic number.

It is an amenable number.

644742677 is a deficient number, since it is larger than the sum of its proper divisors (1).

644742677 is an equidigital number, since it uses as much as digits as its factorization.

644742677 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1580544, while the sum is 47.

The square root of 644742677 is about 25391.7836514098. The cubic root of 644742677 is about 863.8973451461.

The spelling of 644742677 in words is "six hundred forty-four million, seven hundred forty-two thousand, six hundred seventy-seven".