644252645 has 4 divisors (see below), whose sum is σ = 773103180. Its totient is φ = 515402112.

The previous prime is 644252611. The next prime is 644252647. The reversal of 644252645 is 546252446.

644252645 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.

It can be written as a sum of positive squares in 2 ways, for example, as 179720836 + 464531809 = 13406^2 + 21553^2 .

It is a cyclic number.

It is not a de Polignac number, because 644252645 - 2¹⁴ = 644236261 is a prime.

It is a super-2 number, since 2×644252645² = 830122941178992050, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 644252599 and 644252608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644252647) 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, 64425260 + ... + 64425269.

It is an arithmetic number, because the mean of its divisors is an integer number (193275795).

Almost surely, 2^644252645 is an apocalyptic number.

It is an amenable number.

644252645 is a deficient number, since it is larger than the sum of its proper divisors (128850535).

644252645 is a wasteful number, since it uses less digits than its factorization.

644252645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128850534.

The product of its digits is 230400, while the sum is 38.

The square root of 644252645 is about 25382.1323966289. The cubic root of 644252645 is about 863.6784233676.

The spelling of 644252645 in words is "six hundred forty-four million, two hundred fifty-two thousand, six hundred forty-five".