686637225 has 72 divisors (see below), whose sum is σ = 1317471480. Its totient is φ = 340623360.

The previous prime is 686637199. The next prime is 686637229. The reversal of 686637225 is 522736686.

It is a happy number.

686637225 is a `hidden beast` number, since 6 + 8 + 6 + 637 + 2 + 2 + 5 = 666.

It can be written as a sum of positive squares in 12 ways, for example, as 86044176 + 600593049 = 9276^2 + 24507^2 .

It is not a de Polignac number, because 686637225 - 2⁷ = 686637097 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (686637229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 339417 + ... + 341433.

It is an arithmetic number, because the mean of its divisors is an integer number (18298215).

Almost surely, 2^686637225 is an apocalyptic number.

It is an amenable number.

686637225 is a deficient number, since it is larger than the sum of its proper divisors (630834255).

686637225 is a wasteful number, since it uses less digits than its factorization.

686637225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2139 (or 2131 counting only the distinct ones).

The product of its digits is 725760, while the sum is 45.

The square root of 686637225 is about 26203.7635655644. The cubic root of 686637225 is about 882.2177297323.

The spelling of 686637225 in words is "six hundred eighty-six million, six hundred thirty-seven thousand, two hundred twenty-five".