644357745 has 48 divisors (see below), whose sum is σ = 1135622592. Its totient is φ = 337944960.

The previous prime is 644357743. The next prime is 644357759. The reversal of 644357745 is 547753446.

It is not a de Polignac number, because 644357745 - 2¹ = 644357743 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 644357745.

It is not an unprimeable number, because it can be changed into a prime (644357743) 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, 784435 + ... + 785255.

It is an arithmetic number, because the mean of its divisors is an integer number (23658804).

Almost surely, 2^644357745 is an apocalyptic number.

It is an amenable number.

644357745 is a deficient number, since it is larger than the sum of its proper divisors (491264847).

644357745 is a wasteful number, since it uses less digits than its factorization.

644357745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1102 (or 1099 counting only the distinct ones).

The product of its digits is 1411200, while the sum is 45.

The square root of 644357745 is about 25384.2026662253. The cubic root of 644357745 is about 863.7253861377.

The spelling of 644357745 in words is "six hundred forty-four million, three hundred fifty-seven thousand, seven hundred forty-five".