644485279 has 2 divisors, whose sum is σ = 644485280. Its totient is φ = 644485278.

The previous prime is 644485271. The next prime is 644485297. The reversal of 644485279 is 972584446.

Together with next prime (644485297) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644485279 - 2³ = 644485271 is a prime.

It is a super-2 number, since 2×644485279² = 830722549695415682, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644485271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322242639 + 322242640.

It is an arithmetic number, because the mean of its divisors is an integer number (322242640).

Almost surely, 2^644485279 is an apocalyptic number.

644485279 is a deficient number, since it is larger than the sum of its proper divisors (1).

644485279 is an equidigital number, since it uses as much as digits as its factorization.

644485279 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1935360, while the sum is 49.

The square root of 644485279 is about 25386.7146161137. The cubic root of 644485279 is about 863.7823664346.

The spelling of 644485279 in words is "six hundred forty-four million, four hundred eighty-five thousand, two hundred seventy-nine".