644427167 has 4 divisors (see below), whose sum is σ = 650807736. Its totient is φ = 638046600.

The previous prime is 644427139. The next prime is 644427191. The reversal of 644427167 is 761724446.

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 644427167 - 2⁶ = 644427103 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644427107) 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 3 ways as a sum of consecutive naturals, for example, 3190133 + ... + 3190334.

It is an arithmetic number, because the mean of its divisors is an integer number (162701934).

Almost surely, 2^644427167 is an apocalyptic number.

644427167 is a deficient number, since it is larger than the sum of its proper divisors (6380569).

644427167 is a wasteful number, since it uses less digits than its factorization.

644427167 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6380568.

The product of its digits is 225792, while the sum is 41.

The square root of 644427167 is about 25385.5700546590. The cubic root of 644427167 is about 863.7564037885.

The spelling of 644427167 in words is "six hundred forty-four million, four hundred twenty-seven thousand, one hundred sixty-seven".