644422143 has 8 divisors (see below), whose sum is σ = 865789056. Its totient is φ = 426335000.

The previous prime is 644422139. The next prime is 644422151. The reversal of 644422143 is 341224446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644422143 - 2² = 644422139 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644422143.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644422243) 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, 819483 + ... + 820268.

It is an arithmetic number, because the mean of its divisors is an integer number (108223632).

Almost surely, 2^644422143 is an apocalyptic number.

644422143 is a deficient number, since it is larger than the sum of its proper divisors (221366913).

644422143 is a wasteful number, since it uses less digits than its factorization.

644422143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1639885.

The product of its digits is 18432, while the sum is 30.

The square root of 644422143 is about 25385.4711006119. The cubic root of 644422143 is about 863.7541591472.

Adding to 644422143 its reverse (341224446), we get a palindrome (985646589).

The spelling of 644422143 in words is "six hundred forty-four million, four hundred twenty-two thousand, one hundred forty-three".