644718489 has 8 divisors (see below), whose sum is σ = 910190880. Its totient is φ = 404529216.

The previous prime is 644718467. The next prime is 644718493. The reversal of 644718489 is 984817446.

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

It is not a de Polignac number, because 644718489 - 2¹² = 644714393 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51), and also a Moran number because the ratio is a prime number: 12641539 = 644718489 / (6 + 4 + 4 + 7 + 1 + 8 + 4 + 8 + 9).

It is not an unprimeable number, because it can be changed into a prime (644718419) 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, 6320719 + ... + 6320820.

It is an arithmetic number, because the mean of its divisors is an integer number (113773860).

Almost surely, 2^644718489 is an apocalyptic number.

It is an amenable number.

644718489 is a deficient number, since it is larger than the sum of its proper divisors (265472391).

644718489 is a wasteful number, since it uses less digits than its factorization.

644718489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12641559.

The product of its digits is 1548288, while the sum is 51.

The square root of 644718489 is about 25391.3073511389. The cubic root of 644718489 is about 863.8865417610.

The spelling of 644718489 in words is "six hundred forty-four million, seven hundred eighteen thousand, four hundred eighty-nine".