644302231 has 4 divisors (see below), whose sum is σ = 644542432. Its totient is φ = 644062032.

The previous prime is 644302223. The next prime is 644302247. The reversal of 644302231 is 132203446.

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 644302231 - 2³ = 644302223 is a prime.

It is a super-2 number, since 2×644302231² = 830250729743154722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644302196 and 644302205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644302271) 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, 116031 + ... + 121456.

It is an arithmetic number, because the mean of its divisors is an integer number (161135608).

Almost surely, 2^644302231 is an apocalyptic number.

644302231 is a deficient number, since it is larger than the sum of its proper divisors (240201).

644302231 is a wasteful number, since it uses less digits than its factorization.

644302231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240200.

The product of its (nonzero) digits is 3456, while the sum is 25.

The square root of 644302231 is about 25383.1091673183. The cubic root of 644302231 is about 863.7005809584.

Adding to 644302231 its reverse (132203446), we get a palindrome (776505677).

The spelling of 644302231 in words is "six hundred forty-four million, three hundred two thousand, two hundred thirty-one".