686637261 has 6 divisors (see below), whose sum is σ = 991809390. Its totient is φ = 457758168.

The previous prime is 686637233. The next prime is 686637299. The reversal of 686637261 is 162736686.

686637261 is a `hidden beast` number, since 6 + 8 + 6 + 637 + 2 + 6 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 547279236 + 139358025 = 23394^2 + 11805^2 .

It is not a de Polignac number, because 686637261 - 2⁵ = 686637229 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686637461) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 38146506 + ... + 38146523.

It is an arithmetic number, because the mean of its divisors is an integer number (165301565).

Almost surely, 2^686637261 is an apocalyptic number.

It is an amenable number.

686637261 is a deficient number, since it is larger than the sum of its proper divisors (305172129).

686637261 is a wasteful number, since it uses less digits than its factorization.

686637261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76293035 (or 76293032 counting only the distinct ones).

The product of its digits is 435456, while the sum is 45.

The square root of 686637261 is about 26203.7642524886. The cubic root of 686637261 is about 882.2177451503.

The spelling of 686637261 in words is "six hundred eighty-six million, six hundred thirty-seven thousand, two hundred sixty-one".