2556515665 has 16 divisors (see below), whose sum is σ = 3492222336. Its totient is φ = 1778444800.

The previous prime is 2556515639. The next prime is 2556515669. The reversal of 2556515665 is 5665156552.

It is not a de Polignac number, because 2556515665 - 2¹⁹ = 2555991377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2556515669) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 1009216 + ... + 1011745.

It is an arithmetic number, because the mean of its divisors is an integer number (218263896).

Almost surely, 2^2556515665 is an apocalyptic number.

It is an amenable number.

2556515665 is a deficient number, since it is larger than the sum of its proper divisors (935706671).

2556515665 is a wasteful number, since it uses less digits than its factorization.

2556515665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2021000.

The product of its digits is 1350000, while the sum is 46.

The square root of 2556515665 is about 50561.9982298959. The cubic root of 2556515665 is about 1367.3598371095.

The spelling of 2556515665 in words is "two billion, five hundred fifty-six million, five hundred fifteen thousand, six hundred sixty-five".