261561584 has 20 divisors (see below), whose sum is σ = 520473384. Its totient is φ = 127245888.

The previous prime is 261561571. The next prime is 261561611. The reversal of 261561584 is 485165162.

It is a happy number.

It is a hoax number, since the sum of its digits (38) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 220322 + ... + 221505.

Almost surely, 2^261561584 is an apocalyptic number.

It is an amenable number.

261561584 is a deficient number, since it is larger than the sum of its proper divisors (258911800).

261561584 is a wasteful number, since it uses less digits than its factorization.

261561584 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 441872 (or 441866 counting only the distinct ones).

The product of its digits is 57600, while the sum is 38.

The square root of 261561584 is about 16172.8656706225. The cubic root of 261561584 is about 639.5256771981.

The spelling of 261561584 in words is "two hundred sixty-one million, five hundred sixty-one thousand, five hundred eighty-four".