686551 has 2 divisors, whose sum is σ = 686552. Its totient is φ = 686550.

The previous prime is 686519. The next prime is 686563. The reversal of 686551 is 155686.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 686551 - 2⁵ = 686519 is a prime.

It is a nialpdrome in base 15.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (686051) 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 as a sum of consecutive naturals, namely, 343275 + 343276.

It is an arithmetic number, because the mean of its divisors is an integer number (343276).

2⁶⁸⁶⁵⁵¹ is an apocalyptic number.

686551 is a deficient number, since it is larger than the sum of its proper divisors (1).

686551 is an equidigital number, since it uses as much as digits as its factorization.

686551 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7200, while the sum is 31.

The square root of 686551 is about 828.5837314358. The cubic root of 686551 is about 88.2180799795.

The spelling of 686551 in words is "six hundred eighty-six thousand, five hundred fifty-one".