687631817 has 2 divisors, whose sum is σ = 687631818. Its totient is φ = 687631816.

The previous prime is 687631783. The next prime is 687631829. The reversal of 687631817 is 718136786.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 411440656 + 276191161 = 20284^2 + 16619^2 .

It is a cyclic number.

It is not a de Polignac number, because 687631817 - 2⁶ = 687631753 is a prime.

It is not a weakly prime, because it can be changed into another prime (687630817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343815908 + 343815909.

It is an arithmetic number, because the mean of its divisors is an integer number (343815909).

Almost surely, 2^687631817 is an apocalyptic number.

It is an amenable number.

687631817 is a deficient number, since it is larger than the sum of its proper divisors (1).

687631817 is an equidigital number, since it uses as much as digits as its factorization.

687631817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 338688, while the sum is 47.

The square root of 687631817 is about 26222.7347353399. The cubic root of 687631817 is about 882.6434874907.

The spelling of 687631817 in words is "six hundred eighty-seven million, six hundred thirty-one thousand, eight hundred seventeen".