261565668426 has 32 divisors (see below), whose sum is σ = 532100044800. Its totient is φ = 85694338800.

The previous prime is 261565668421. The next prime is 261565668473. The reversal of 261565668426 is 624866565162.

It is a happy number.

It is a Smith number, since the sum of its digits (57) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (261565668421) 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, 1850151 + ... + 1986501.

It is an arithmetic number, because the mean of its divisors is an integer number (16628126400).

Almost surely, 2^261565668426 is an apocalyptic number.

261565668426 is an abundant number, since it is smaller than the sum of its proper divisors (270534376374).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261565668426 is a wasteful number, since it uses less digits than its factorization.

261565668426 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141834.

The product of its digits is 24883200, while the sum is 57.

The spelling of 261565668426 in words is "two hundred sixty-one billion, five hundred sixty-five million, six hundred sixty-eight thousand, four hundred twenty-six".