644718241 has 4 divisors (see below), whose sum is σ = 678650800. Its totient is φ = 610785684.

The previous prime is 644718197. The next prime is 644718247. The reversal of 644718241 is 142817446.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 644718241 - 2¹⁷ = 644587169 is a prime.

It is a super-2 number, since 2×644718241² = 831323220556268162, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644718241.

It is not an unprimeable number, because it can be changed into a prime (644718247) 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, 16966251 + ... + 16966288.

It is an arithmetic number, because the mean of its divisors is an integer number (169662700).

Almost surely, 2^644718241 is an apocalyptic number.

It is an amenable number.

644718241 is a deficient number, since it is larger than the sum of its proper divisors (33932559).

644718241 is a wasteful number, since it uses less digits than its factorization.

644718241 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33932558.

The product of its digits is 43008, while the sum is 37.

The square root of 644718241 is about 25391.3024675774. The cubic root of 644718241 is about 863.8864309923.

The spelling of 644718241 in words is "six hundred forty-four million, seven hundred eighteen thousand, two hundred forty-one".