261686787850 has 12 divisors (see below), whose sum is σ = 486737425494. Its totient is φ = 104674715120.

The previous prime is 261686787841. The next prime is 261686787899. The reversal of 261686787850 is 58787686162.

It can be written as a sum of positive squares in 3 ways, for example, as 251084172889 + 10602614961 = 501083^2 + 102969^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2616867829 + ... + 2616867928.

Almost surely, 2^261686787850 is an apocalyptic number.

261686787850 is a deficient number, since it is larger than the sum of its proper divisors (225050637644).

261686787850 is a wasteful number, since it uses less digits than its factorization.

261686787850 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5233735769 (or 5233735764 counting only the distinct ones).

The product of its (nonzero) digits is 54190080, while the sum is 64.

The spelling of 261686787850 in words is "two hundred sixty-one billion, six hundred eighty-six million, seven hundred eighty-seven thousand, eight hundred fifty".