686656161 has 6 divisors (see below), whose sum is σ = 991836690. Its totient is φ = 457770768.

The previous prime is 686656109. The next prime is 686656183. The reversal of 686656161 is 161656686.

686656161 is a `hidden beast` number, since 6 + 86 + 6 + 561 + 6 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 612265536 + 74390625 = 24744^2 + 8625^2 .

It is not a de Polignac number, because 686656161 - 2⁶ = 686656097 is a prime.

It is not an unprimeable number, because it can be changed into a prime (686656961) 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, 38147556 + ... + 38147573.

It is an arithmetic number, because the mean of its divisors is an integer number (165306115).

Almost surely, 2^686656161 is an apocalyptic number.

It is an amenable number.

686656161 is a deficient number, since it is larger than the sum of its proper divisors (305180529).

686656161 is a wasteful number, since it uses less digits than its factorization.

686656161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76295135 (or 76295132 counting only the distinct ones).

The product of its digits is 311040, while the sum is 45.

The square root of 686656161 is about 26204.1248852161. The cubic root of 686656161 is about 882.2258395564.

The spelling of 686656161 in words is "six hundred eighty-six million, six hundred fifty-six thousand, one hundred sixty-one".