644742719 has 2 divisors, whose sum is σ = 644742720. Its totient is φ = 644742718.

The previous prime is 644742677. The next prime is 644742727. The reversal of 644742719 is 917247446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644742719 - 2¹⁶ = 644677183 is a prime.

It is a super-2 number, since 2×644742719² = 831386347407025922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 644742719.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644741719) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322371359 + 322371360.

It is an arithmetic number, because the mean of its divisors is an integer number (322371360).

Almost surely, 2^644742719 is an apocalyptic number.

644742719 is a deficient number, since it is larger than the sum of its proper divisors (1).

644742719 is an equidigital number, since it uses as much as digits as its factorization.

644742719 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 338688, while the sum is 44.

The square root of 644742719 is about 25391.7844784489. The cubic root of 644742719 is about 863.8973639048.

It can be divided in two parts, 6447427 and 19, that added together give a palindrome (6447446).

The spelling of 644742719 in words is "six hundred forty-four million, seven hundred forty-two thousand, seven hundred nineteen".