688669 has 2 divisors, whose sum is σ = 688670. Its totient is φ = 688668.

The previous prime is 688661. The next prime is 688679. The reversal of 688669 is 966886.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 632025 + 56644 = 795^2 + 238^2 .

It is a cyclic number.

It is not a de Polignac number, because 688669 - 2³ = 688661 is a prime.

It is a super-2 number, since 2×688669² = 948529983122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (688661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344334 + 344335.

It is an arithmetic number, because the mean of its divisors is an integer number (344335).

2⁶⁸⁸⁶⁶⁹ is an apocalyptic number.

It is an amenable number.

688669 is a deficient number, since it is larger than the sum of its proper divisors (1).

688669 is an equidigital number, since it uses as much as digits as its factorization.

688669 is an evil number, because the sum of its binary digits is even.

The product of its digits is 124416, while the sum is 43.

The square root of 688669 is about 829.8608317061. The cubic root of 688669 is about 88.3087040230.

The spelling of 688669 in words is "six hundred eighty-eight thousand, six hundred sixty-nine".