644760145 has 4 divisors (see below), whose sum is σ = 773712180. Its totient is φ = 515808112.

The previous prime is 644760119. The next prime is 644760167. The reversal of 644760145 is 541067446.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 326922561 + 317837584 = 18081^2 + 17828^2 .

It is a cyclic number.

It is not a de Polignac number, because 644760145 - 2²⁹ = 107889233 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64476010 + ... + 64476019.

It is an arithmetic number, because the mean of its divisors is an integer number (193428045).

Almost surely, 2^644760145 is an apocalyptic number.

It is an amenable number.

644760145 is a deficient number, since it is larger than the sum of its proper divisors (128952035).

644760145 is a wasteful number, since it uses less digits than its factorization.

644760145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128952034.

The product of its (nonzero) digits is 80640, while the sum is 37.

The square root of 644760145 is about 25392.1276186144. The cubic root of 644760145 is about 863.9051469266.

The spelling of 644760145 in words is "six hundred forty-four million, seven hundred sixty thousand, one hundred forty-five".