644493371 has 4 divisors (see below), whose sum is σ = 644826000. Its totient is φ = 644160744.

The previous prime is 644493359. The next prime is 644493383. The reversal of 644493371 is 173394446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 173394446 = 2 ⋅86697223.

It is an interprime number because it is at equal distance from previous prime (644493359) and next prime (644493383).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644493371 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644493271) 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, 163391 + ... + 167288.

It is an arithmetic number, because the mean of its divisors is an integer number (161206500).

Almost surely, 2^644493371 is an apocalyptic number.

644493371 is a deficient number, since it is larger than the sum of its proper divisors (332629).

644493371 is a wasteful number, since it uses less digits than its factorization.

644493371 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332628.

The product of its digits is 217728, while the sum is 41.

The square root of 644493371 is about 25386.8739903124. The cubic root of 644493371 is about 863.7859815664.

The spelling of 644493371 in words is "six hundred forty-four million, four hundred ninety-three thousand, three hundred seventy-one".