686121998 has 8 divisors (see below), whose sum is σ = 1030284192. Its totient is φ = 342693936.

The previous prime is 686121971. The next prime is 686122001. The reversal of 686121998 is 899121686.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×686121998² = 941526792279024008, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 181190 + ... + 184937.

It is an arithmetic number, because the mean of its divisors is an integer number (128785524).

Almost surely, 2^686121998 is an apocalyptic number.

686121998 is a deficient number, since it is larger than the sum of its proper divisors (344162194).

686121998 is a wasteful number, since it uses less digits than its factorization.

686121998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 367066.

The product of its digits is 373248, while the sum is 50.

The square root of 686121998 is about 26193.9305565240. The cubic root of 686121998 is about 881.9970134085.

The spelling of 686121998 in words is "six hundred eighty-six million, one hundred twenty-one thousand, nine hundred ninety-eight".