645312254561 has 16 divisors (see below), whose sum is σ = 718984017360. Its totient is φ = 575077601280.

The previous prime is 645312254557. The next prime is 645312254567. The reversal of 645312254561 is 165452213546.

It can be written as a sum of positive squares in 8 ways, for example, as 261105670225 + 384206584336 = 510985^2 + 619844^2 .

It is not a de Polignac number, because 645312254561 - 2² = 645312254557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645312254567) 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, 4174001 + ... + 4325841.

It is an arithmetic number, because the mean of its divisors is an integer number (44936501085).

Almost surely, 2^645312254561 is an apocalyptic number.

It is an amenable number.

645312254561 is a deficient number, since it is larger than the sum of its proper divisors (73671762799).

645312254561 is a wasteful number, since it uses less digits than its factorization.

645312254561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163156.

The product of its digits is 864000, while the sum is 44.

The spelling of 645312254561 in words is "six hundred forty-five billion, three hundred twelve million, two hundred fifty-four thousand, five hundred sixty-one".