644747311 has 16 divisors (see below), whose sum is σ = 750652000. Its totient is φ = 548581248.

The previous prime is 644747309. The next prime is 644747333. The reversal of 644747311 is 113747446.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 644747311 - 2¹ = 644747309 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644747351) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26136 + ... + 44413.

It is an arithmetic number, because the mean of its divisors is an integer number (46915750).

Almost surely, 2^644747311 is an apocalyptic number.

644747311 is a deficient number, since it is larger than the sum of its proper divisors (105904689).

644747311 is a wasteful number, since it uses less digits than its factorization.

644747311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70618.

The product of its digits is 56448, while the sum is 37.

The square root of 644747311 is about 25391.8749012356. The cubic root of 644747311 is about 863.8994148559.

The spelling of 644747311 in words is "six hundred forty-four million, seven hundred forty-seven thousand, three hundred eleven".