686138872225 has 9 divisors (see below), whose sum is σ = 850817337267. Its totient is φ = 548907784440.

The previous prime is 686138872201. The next prime is 686138872229. The reversal of 686138872225 is 522278831686.

The square root of 686138872225 is 828335.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 247009994001 + 439128878224 = 497001^2 + 662668^2 .

It is not a de Polignac number, because 686138872225 - 2¹⁵ = 686138839457 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 686138872225.

It is not an unprimeable number, because it can be changed into a prime (686138872229) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 4058842 + ... + 4224508.

Almost surely, 2^686138872225 is an apocalyptic number.

686138872225 is the 828335-th square number.

686138872225 is the 414168-th centered octagonal number.

It is an amenable number.

686138872225 is a deficient number, since it is larger than the sum of its proper divisors (164678465042).

686138872225 is an frugal number, since it uses more digits than its factorization.

686138872225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331344 (or 165672 counting only the distinct ones).

The product of its digits is 15482880, while the sum is 58.

The spelling of 686138872225 in words is "six hundred eighty-six billion, one hundred thirty-eight million, eight hundred seventy-two thousand, two hundred twenty-five".