644374942291 has 4 divisors (see below), whose sum is σ = 665161230784. Its totient is φ = 623588653800.

The previous prime is 644374942279. The next prime is 644374942301. The reversal of 644374942291 is 192249473446.

It is a happy number.

644374942291 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 192249473446 = 2 ⋅96124736723.

It is a cyclic number.

It is not a de Polignac number, because 644374942291 - 2⁷ = 644374942163 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644374942271) 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, 10393144200 + ... + 10393144261.

It is an arithmetic number, because the mean of its divisors is an integer number (166290307696).

Almost surely, 2^644374942291 is an apocalyptic number.

644374942291 is a deficient number, since it is larger than the sum of its proper divisors (20786288493).

644374942291 is a wasteful number, since it uses less digits than its factorization.

644374942291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20786288492.

The product of its digits is 10450944, while the sum is 55.

The spelling of 644374942291 in words is "six hundred forty-four billion, three hundred seventy-four million, nine hundred forty-two thousand, two hundred ninety-one".