261685287 has 12 divisors (see below), whose sum is σ = 381336384. Its totient is φ = 172912320.

The previous prime is 261685279. The next prime is 261685351. The reversal of 261685287 is 782586162.

261685287 is a `hidden beast` number, since 2 + 61 + 68 + 528 + 7 = 666.

It is not a de Polignac number, because 261685287 - 2³ = 261685279 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261685387) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 127639 + ... + 129672.

It is an arithmetic number, because the mean of its divisors is an integer number (31778032).

Almost surely, 2^261685287 is an apocalyptic number.

261685287 is a deficient number, since it is larger than the sum of its proper divisors (119651097).

261685287 is a wasteful number, since it uses less digits than its factorization.

261685287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 257430 (or 257427 counting only the distinct ones).

The product of its digits is 322560, while the sum is 45.

The square root of 261685287 is about 16176.6896180894. The cubic root of 261685287 is about 639.6264804523.

The spelling of 261685287 in words is "two hundred sixty-one million, six hundred eighty-five thousand, two hundred eighty-seven".