688990 has 8 divisors (see below), whose sum is σ = 1240200. Its totient is φ = 275592.

The previous prime is 688979. The next prime is 688999. The reversal of 688990 is 99886.

It is a happy number.

688990 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34440 + ... + 34459.

It is an arithmetic number, because the mean of its divisors is an integer number (155025).

2⁶⁸⁸⁹⁹⁰ is an apocalyptic number.

688990 is a deficient number, since it is larger than the sum of its proper divisors (551210).

688990 is a wasteful number, since it uses less digits than its factorization.

688990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68906.

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 688990 is about 830.0542150968. The cubic root of 688990 is about 88.3224226071.

The spelling of 688990 in words is "six hundred eighty-eight thousand, nine hundred ninety".