644648445 has 48 divisors (see below), whose sum is σ = 1285569792. Its totient is φ = 292723200.

The previous prime is 644648443. The next prime is 644648461. The reversal of 644648445 is 544846446.

It is not a de Polignac number, because 644648445 - 2¹ = 644648443 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 644648445.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644648443) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 40789 + ... + 54341.

It is an arithmetic number, because the mean of its divisors is an integer number (26782704).

Almost surely, 2^644648445 is an apocalyptic number.

It is an amenable number.

644648445 is a deficient number, since it is larger than the sum of its proper divisors (640921347).

644648445 is a wasteful number, since it uses less digits than its factorization.

644648445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13722 (or 13719 counting only the distinct ones).

The product of its digits is 1474560, while the sum is 45.

The square root of 644648445 is about 25389.9280227416. The cubic root of 644648445 is about 863.8552556201.

The spelling of 644648445 in words is "six hundred forty-four million, six hundred forty-eight thousand, four hundred forty-five".