644673299 has 4 divisors (see below), whose sum is σ = 660397080. Its totient is φ = 628949520.

The previous prime is 644673257. The next prime is 644673317. The reversal of 644673299 is 992376446.

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

It is a cyclic number.

It is not a de Polignac number, because 644673299 - 2¹⁶ = 644607763 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644673229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7861829 + ... + 7861910.

It is an arithmetic number, because the mean of its divisors is an integer number (165099270).

Almost surely, 2^644673299 is an apocalyptic number.

644673299 is a deficient number, since it is larger than the sum of its proper divisors (15723781).

644673299 is a wasteful number, since it uses less digits than its factorization.

644673299 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15723780.

The product of its digits is 1959552, while the sum is 50.

The square root of 644673299 is about 25390.4174640749. The cubic root of 644673299 is about 863.8663572693.

The spelling of 644673299 in words is "six hundred forty-four million, six hundred seventy-three thousand, two hundred ninety-nine".