688949691 has 24 divisors (see below), whose sum is σ = 957351024. Its totient is φ = 440363520.

The previous prime is 688949687. The next prime is 688949711. The reversal of 688949691 is 196949886.

It is not a de Polignac number, because 688949691 - 2² = 688949687 is a prime.

It is a super-3 number, since 3×688949691³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688949791) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 2487045 + ... + 2487321.

It is an arithmetic number, because the mean of its divisors is an integer number (39889626).

Almost surely, 2^688949691 is an apocalyptic number.

688949691 is a deficient number, since it is larger than the sum of its proper divisors (268401333).

688949691 is an equidigital number, since it uses as much as digits as its factorization.

688949691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 671 (or 394 counting only the distinct ones).

The product of its digits is 6718464, while the sum is 60.

The square root of 688949691 is about 26247.8511691910. The cubic root of 688949691 is about 883.2070015448.

The spelling of 688949691 in words is "six hundred eighty-eight million, nine hundred forty-nine thousand, six hundred ninety-one".