687684857 has 2 divisors, whose sum is σ = 687684858. Its totient is φ = 687684856.

The previous prime is 687684817. The next prime is 687684863. The reversal of 687684857 is 758486786.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 405982201 + 281702656 = 20149^2 + 16784^2 .

It is a cyclic number.

It is not a de Polignac number, because 687684857 - 2¹⁴ = 687668473 is a prime.

It is a super-2 number, since 2×687684857² = 945820925094220898, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 687684796 and 687684805.

It is not a weakly prime, because it can be changed into another prime (687684817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343842428 + 343842429.

It is an arithmetic number, because the mean of its divisors is an integer number (343842429).

Almost surely, 2^687684857 is an apocalyptic number.

It is an amenable number.

687684857 is a deficient number, since it is larger than the sum of its proper divisors (1).

687684857 is an equidigital number, since it uses as much as digits as its factorization.

687684857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18063360, while the sum is 59.

The square root of 687684857 is about 26223.7460520041. The cubic root of 687684857 is about 882.6661809369. Note that the first 3 decimals are identical.

The spelling of 687684857 in words is "six hundred eighty-seven million, six hundred eighty-four thousand, eight hundred fifty-seven".