644575145 has 16 divisors (see below), whose sum is σ = 838969488. Its totient is φ = 473487360.

The previous prime is 644575093. The next prime is 644575153. The reversal of 644575145 is 541575446.

It can be written as a sum of positive squares in 8 ways, for example, as 1597696 + 642977449 = 1264^2 + 25357^2 .

It is not a de Polignac number, because 644575145 - 2¹² = 644571049 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 88994 + ... + 95963.

It is an arithmetic number, because the mean of its divisors is an integer number (52435593).

Almost surely, 2^644575145 is an apocalyptic number.

It is an amenable number.

644575145 is a deficient number, since it is larger than the sum of its proper divisors (194394343).

644575145 is a wasteful number, since it uses less digits than its factorization.

644575145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185020.

The product of its digits is 336000, while the sum is 41.

The square root of 644575145 is about 25388.4844959285. The cubic root of 644575145 is about 863.8225127141.

The spelling of 644575145 in words is "six hundred forty-four million, five hundred seventy-five thousand, one hundred forty-five".