688721652 has 72 divisors (see below), whose sum is σ = 1843019360. Its totient is φ = 216250560.

The previous prime is 688721647. The next prime is 688721681. The reversal of 688721652 is 256127886.

It is a junction number, because it is equal to n+sod(n) for n = 688721598 and 688721607.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 121023 + ... + 126585.

Almost surely, 2^688721652 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 688721652, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (921509680).

688721652 is an abundant number, since it is smaller than the sum of its proper divisors (1154297708).

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

688721652 is a wasteful number, since it uses less digits than its factorization.

688721652 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5773 (or 5768 counting only the distinct ones).

The product of its digits is 322560, while the sum is 45.

The square root of 688721652 is about 26243.5068540773. The cubic root of 688721652 is about 883.1095450495.

The spelling of 688721652 in words is "six hundred eighty-eight million, seven hundred twenty-one thousand, six hundred fifty-two".