644459489 has 8 divisors (see below), whose sum is σ = 679262760. Its totient is φ = 610494976.

The previous prime is 644459483. The next prime is 644459503. The reversal of 644459489 is 984954446.

It can be written as a sum of positive squares in 4 ways, for example, as 17808400 + 626651089 = 4220^2 + 25033^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644459489 is a prime.

It is a super-2 number, since 2×644459489² = 830656065924282242, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (53).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644459489.

It is not an unprimeable number, because it can be changed into a prime (644459483) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 208112 + ... + 211185.

It is an arithmetic number, because the mean of its divisors is an integer number (84907845).

Almost surely, 2^644459489 is an apocalyptic number.

It is an amenable number.

644459489 is a deficient number, since it is larger than the sum of its proper divisors (34803271).

644459489 is a wasteful number, since it uses less digits than its factorization.

644459489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 419379.

The product of its digits is 4976640, while the sum is 53.

The square root of 644459489 is about 25386.2066681889. The cubic root of 644459489 is about 863.7708444521.

The spelling of 644459489 in words is "six hundred forty-four million, four hundred fifty-nine thousand, four hundred eighty-nine".