261011863818 has 12 divisors (see below), whose sum is σ = 565525704978. Its totient is φ = 87003954600.

The previous prime is 261011863757. The next prime is 261011863909. The reversal of 261011863818 is 818368110162.

261011863818 is a `hidden beast` number, since 2 + 6 + 1 + 0 + 1 + 1 + 8 + 638 + 1 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 243871031889 + 17140831929 = 493833^2 + 130923^2 .

It is a Curzon number.

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, 7250329533 + ... + 7250329568.

Almost surely, 2^261011863818 is an apocalyptic number.

261011863818 is an abundant number, since it is smaller than the sum of its proper divisors (304513841160).

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

261011863818 is a wasteful number, since it uses less digits than its factorization.

261011863818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14500659109 (or 14500659106 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 45.

The spelling of 261011863818 in words is "two hundred sixty-one billion, eleven million, eight hundred sixty-three thousand, eight hundred eighteen".