687993217 has 2 divisors, whose sum is σ = 687993218. Its totient is φ = 687993216.

The previous prime is 687993209. The next prime is 687993221. The reversal of 687993217 is 712399786.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 663629121 + 24364096 = 25761^2 + 4936^2 .

It is a cyclic number.

It is not a de Polignac number, because 687993217 - 2³ = 687993209 is a prime.

It is not a weakly prime, because it can be changed into another prime (687993017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343996608 + 343996609.

It is an arithmetic number, because the mean of its divisors is an integer number (343996609).

Almost surely, 2^687993217 is an apocalyptic number.

It is an amenable number.

687993217 is a deficient number, since it is larger than the sum of its proper divisors (1).

687993217 is an equidigital number, since it uses as much as digits as its factorization.

687993217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1143072, while the sum is 52.

The square root of 687993217 is about 26229.6247971640. The cubic root of 687993217 is about 882.7980912971.

The spelling of 687993217 in words is "six hundred eighty-seven million, nine hundred ninety-three thousand, two hundred seventeen".