645520515125 has 16 divisors (see below), whose sum is σ = 805671567792. Its totient is φ = 516376691200.

The previous prime is 645520515121. The next prime is 645520515181. The reversal of 645520515125 is 521515025546.

It can be written as a sum of positive squares in 8 ways, for example, as 95303716369 + 550216798756 = 308713^2 + 741766^2 .

It is not a de Polignac number, because 645520515125 - 2² = 645520515121 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645520515121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1490249 + ... + 1874001.

It is an arithmetic number, because the mean of its divisors is an integer number (50354472987).

Almost surely, 2^645520515125 is an apocalyptic number.

It is an amenable number.

645520515125 is a deficient number, since it is larger than the sum of its proper divisors (160151052667).

645520515125 is a wasteful number, since it uses less digits than its factorization.

645520515125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397225 (or 397215 counting only the distinct ones).

The product of its (nonzero) digits is 300000, while the sum is 41.

The spelling of 645520515125 in words is "six hundred forty-five billion, five hundred twenty million, five hundred fifteen thousand, one hundred twenty-five".