261866161569 has 16 divisors (see below), whose sum is σ = 376668755712. Its totient is φ = 161208023808.

The previous prime is 261866161561. The next prime is 261866161619. The reversal of 261866161569 is 965161668162.

It is not a de Polignac number, because 261866161569 - 2³ = 261866161561 is a prime.

It is a super-2 number, since 2×261866161569² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261866161561) 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, 48437209 + ... + 48442614.

It is an arithmetic number, because the mean of its divisors is an integer number (23541797232).

Almost surely, 2^261866161569 is an apocalyptic number.

It is an amenable number.

261866161569 is a deficient number, since it is larger than the sum of its proper divisors (114802594143).

261866161569 is a wasteful number, since it uses less digits than its factorization.

261866161569 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96879896.

The product of its digits is 5598720, while the sum is 57.

The spelling of 261866161569 in words is "two hundred sixty-one billion, eight hundred sixty-six million, one hundred sixty-one thousand, five hundred sixty-nine".