644216171 has 4 divisors (see below), whose sum is σ = 644319144. Its totient is φ = 644113200.

The previous prime is 644216161. The next prime is 644216191. The reversal of 644216171 is 171612446.

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 644216171 - 2¹⁸ = 643954027 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644216161) 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, 41450 + ... + 54831.

It is an arithmetic number, because the mean of its divisors is an integer number (161079786).

Almost surely, 2^644216171 is an apocalyptic number.

644216171 is a deficient number, since it is larger than the sum of its proper divisors (102973).

644216171 is an equidigital number, since it uses as much as digits as its factorization.

644216171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102972.

The product of its digits is 8064, while the sum is 32.

The square root of 644216171 is about 25381.4138889070. The cubic root of 644216171 is about 863.6621241711.

The spelling of 644216171 in words is "six hundred forty-four million, two hundred sixteen thousand, one hundred seventy-one".