686555091 has 24 divisors (see below), whose sum is σ = 1019920304. Its totient is φ = 444709440.

The previous prime is 686554997. The next prime is 686555119. The reversal of 686555091 is 190555686.

It is a happy number.

686555091 is a `hidden beast` number, since 6 + 8 + 6 + 5 + 550 + 91 = 666.

It is not a de Polignac number, because 686555091 - 2⁹ = 686554579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (686545091) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 429105 + ... + 430701.

Almost surely, 2^686555091 is an apocalyptic number.

686555091 is a deficient number, since it is larger than the sum of its proper divisors (333365213).

686555091 is a wasteful number, since it uses less digits than its factorization.

686555091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2931 (or 2928 counting only the distinct ones).

The product of its (nonzero) digits is 324000, while the sum is 45.

The square root of 686555091 is about 26202.1963010737. The cubic root of 686555091 is about 882.1825520296.

The spelling of 686555091 in words is "six hundred eighty-six million, five hundred fifty-five thousand, ninety-one".