644599729 has 4 divisors (see below), whose sum is σ = 644719680. Its totient is φ = 644479780.

The previous prime is 644599687. The next prime is 644599741. The reversal of 644599729 is 927995446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 644599729 - 2⁷ = 644599601 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644599729.

It is not an unprimeable number, because it can be changed into a prime (644599129) 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, 51517 + ... + 62794.

It is an arithmetic number, because the mean of its divisors is an integer number (161179920).

Almost surely, 2^644599729 is an apocalyptic number.

It is an amenable number.

644599729 is a deficient number, since it is larger than the sum of its proper divisors (119951).

644599729 is a wasteful number, since it uses less digits than its factorization.

644599729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119950.

The product of its digits is 4898880, while the sum is 55.

The square root of 644599729 is about 25388.9686478203. The cubic root of 644599729 is about 863.8334945951.

The spelling of 644599729 in words is "six hundred forty-four million, five hundred ninety-nine thousand, seven hundred twenty-nine".