644797743 has 16 divisors (see below), whose sum is σ = 911865600. Its totient is φ = 403884416.

The previous prime is 644797739. The next prime is 644797793. The reversal of 644797743 is 347797446.

It is a cyclic number.

It is not a de Polignac number, because 644797743 - 2² = 644797739 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644797793) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19996 + ... + 41102.

It is an arithmetic number, because the mean of its divisors is an integer number (56991600).

Almost surely, 2^644797743 is an apocalyptic number.

644797743 is a deficient number, since it is larger than the sum of its proper divisors (267067857).

644797743 is a wasteful number, since it uses less digits than its factorization.

644797743 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21726.

The product of its digits is 3556224, while the sum is 51.

The square root of 644797743 is about 25392.8679553925. The cubic root of 644797743 is about 863.9219389459.

The spelling of 644797743 in words is "six hundred forty-four million, seven hundred ninety-seven thousand, seven hundred forty-three".