645918725291 has 16 divisors (see below), whose sum is σ = 756679408128. Its totient is φ = 539796897600.

The previous prime is 645918725237. The next prime is 645918725293. The reversal of 645918725291 is 192527819546.

It is a cyclic number.

It is not a de Polignac number, because 645918725291 - 2²⁶ = 645851616427 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 645918725291.

It is not an unprimeable number, because it can be changed into a prime (645918725293) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 265415 + ... + 1167168.

It is an arithmetic number, because the mean of its divisors is an integer number (47292463008).

Almost surely, 2^645918725291 is an apocalyptic number.

645918725291 is a deficient number, since it is larger than the sum of its proper divisors (110760682837).

645918725291 is a wasteful number, since it uses less digits than its factorization.

645918725291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1434202.

The product of its digits is 10886400, while the sum is 59.

The spelling of 645918725291 in words is "six hundred forty-five billion, nine hundred eighteen million, seven hundred twenty-five thousand, two hundred ninety-one".