644254463441 has 4 divisors (see below), whose sum is σ = 654816012084. Its totient is φ = 633692914800.

The previous prime is 644254463389. The next prime is 644254463471. The reversal of 644254463441 is 144364452446.

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 157294732816 + 486959730625 = 396604^2 + 697825^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644254463441 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644254463471) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5280774230 + ... + 5280774351.

It is an arithmetic number, because the mean of its divisors is an integer number (163704003021).

Almost surely, 2^644254463441 is an apocalyptic number.

644254463441 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

644254463441 is a deficient number, since it is larger than the sum of its proper divisors (10561548643).

644254463441 is a wasteful number, since it uses less digits than its factorization.

644254463441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10561548642.

The product of its digits is 4423680, while the sum is 47.

The spelling of 644254463441 in words is "six hundred forty-four billion, two hundred fifty-four million, four hundred sixty-three thousand, four hundred forty-one".