644744799 has 8 divisors (see below), whose sum is σ = 955177520. Its totient is φ = 429829848.

The previous prime is 644744797. The next prime is 644744801. The reversal of 644744799 is 997447446.

It is an interprime number because it is at equal distance from previous prime (644744797) and next prime (644744801).

It is not a de Polignac number, because 644744799 - 2¹ = 644744797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644744797) 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, 11939692 + ... + 11939745.

It is an arithmetic number, because the mean of its divisors is an integer number (119397190).

Almost surely, 2^644744799 is an apocalyptic number.

644744799 is a deficient number, since it is larger than the sum of its proper divisors (310432721).

644744799 is a wasteful number, since it uses less digits than its factorization.

644744799 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23879446 (or 23879440 counting only the distinct ones).

The product of its digits is 6096384, while the sum is 54.

The square root of 644744799 is about 25391.8254365455. The cubic root of 644744799 is about 863.8982929083.

The spelling of 644744799 in words is "six hundred forty-four million, seven hundred forty-four thousand, seven hundred ninety-nine".