261287565218 has 16 divisors (see below), whose sum is σ = 405476928000. Its totient is φ = 126129271632.

The previous prime is 261287565197. The next prime is 261287565251. The reversal of 261287565218 is 812565782162.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 261287565218.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 634313 + ... + 961731.

It is an arithmetic number, because the mean of its divisors is an integer number (25342308000).

Almost surely, 2^261287565218 is an apocalyptic number.

261287565218 is a deficient number, since it is larger than the sum of its proper divisors (144189362782).

261287565218 is a wasteful number, since it uses less digits than its factorization.

261287565218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 341209.

The product of its digits is 3225600, while the sum is 53.

The spelling of 261287565218 in words is "two hundred sixty-one billion, two hundred eighty-seven million, five hundred sixty-five thousand, two hundred eighteen".