643565725 has 36 divisors (see below), whose sum is σ = 898731540. Its totient is φ = 456544000.

The previous prime is 643565711. The next prime is 643565749. The reversal of 643565725 is 527565346.

It can be written as a sum of positive squares in 6 ways, for example, as 45616516 + 597949209 = 6754^2 + 24453^2 .

It is not a de Polignac number, because 643565725 - 2⁵ = 643565693 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 121431 + ... + 126619.

It is an arithmetic number, because the mean of its divisors is an integer number (24964765).

Almost surely, 2^643565725 is an apocalyptic number.

It is an amenable number.

643565725 is a deficient number, since it is larger than the sum of its proper divisors (255165815).

643565725 is a wasteful number, since it uses less digits than its factorization.

643565725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5262 (or 5246 counting only the distinct ones).

The product of its digits is 756000, while the sum is 43.

The square root of 643565725 is about 25368.5972217622. The cubic root of 643565725 is about 863.3713549275.

The spelling of 643565725 in words is "six hundred forty-three million, five hundred sixty-five thousand, seven hundred twenty-five".