261583866 has 12 divisors (see below), whose sum is σ = 566765082. Its totient is φ = 87194616.

The previous prime is 261583841. The next prime is 261583871. The reversal of 261583866 is 668385162.

261583866 is a `hidden beast` number, since 2 + 6 + 1 + 583 + 8 + 66 = 666.

It can be written as a sum of positive squares in only one way, i.e., 218300625 + 43283241 = 14775^2 + 6579^2 .

It is a super-2 number, since 2×261583866² = 136852237903011912, which contains 22 as substring.

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, 7266201 + ... + 7266236.

Almost surely, 2^261583866 is an apocalyptic number.

261583866 is an abundant number, since it is smaller than the sum of its proper divisors (305181216).

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

261583866 is a wasteful number, since it uses less digits than its factorization.

261583866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14532445 (or 14532442 counting only the distinct ones).

The product of its digits is 414720, while the sum is 45.

The square root of 261583866 is about 16173.5545258301. The cubic root of 261583866 is about 639.5438367284.

The spelling of 261583866 in words is "two hundred sixty-one million, five hundred eighty-three thousand, eight hundred sixty-six".