688720308 has 12 divisors (see below), whose sum is σ = 1607014080. Its totient is φ = 229573432.

The previous prime is 688720301. The next prime is 688720309. The reversal of 688720308 is 803027886.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×688720308² = 948671325303229728, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 688720308.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688720301) 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, 28696668 + ... + 28696691.

It is an arithmetic number, because the mean of its divisors is an integer number (133917840).

Almost surely, 2^688720308 is an apocalyptic number.

It is an amenable number.

688720308 is an abundant number, since it is smaller than the sum of its proper divisors (918293772).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

688720308 is a wasteful number, since it uses less digits than its factorization.

688720308 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57393366 (or 57393364 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 42.

The square root of 688720308 is about 26243.4812477308. The cubic root of 688720308 is about 883.1089706036.

The spelling of 688720308 in words is "six hundred eighty-eight million, seven hundred twenty thousand, three hundred eight".