644789131 has 8 divisors (see below), whose sum is σ = 739839744. Its totient is φ = 550473000.

The previous prime is 644789129. The next prime is 644789137. The reversal of 644789131 is 131987446.

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

It is not a de Polignac number, because 644789131 - 2¹ = 644789129 is a prime.

It is a super-2 number, since 2×644789131² = 831506046911470322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (644789137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 181735 + ... + 185248.

It is an arithmetic number, because the mean of its divisors is an integer number (92479968).

Almost surely, 2^644789131 is an apocalyptic number.

644789131 is a deficient number, since it is larger than the sum of its proper divisors (95050613).

644789131 is a wasteful number, since it uses less digits than its factorization.

644789131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 367241.

The product of its digits is 145152, while the sum is 43.

The square root of 644789131 is about 25392.6983796524. The cubic root of 644789131 is about 863.9180927120.

The spelling of 644789131 in words is "six hundred forty-four million, seven hundred eighty-nine thousand, one hundred thirty-one".