686121 has 4 divisors (see below), whose sum is σ = 914832. Its totient is φ = 457412.

The previous prime is 686117. The next prime is 686131. The reversal of 686121 is 121686.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 686121 - 2² = 686117 is a prime.

It is a D-number.

It is a Curzon number.

686121 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 686091 and 686100.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 686121.

It is not an unprimeable number, because it can be changed into a prime (686131) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 114351 + ... + 114356.

It is an arithmetic number, because the mean of its divisors is an integer number (228708).

2⁶⁸⁶¹²¹ is an apocalyptic number.

It is an amenable number.

686121 is a deficient number, since it is larger than the sum of its proper divisors (228711).

686121 is a wasteful number, since it uses less digits than its factorization.

686121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228710.

The product of its digits is 576, while the sum is 24.

The square root of 686121 is about 828.3242118881. The cubic root of 686121 is about 88.1996585772.

The spelling of 686121 in words is "six hundred eighty-six thousand, one hundred twenty-one".