688925661 has 16 divisors (see below), whose sum is σ = 944074560. Its totient is φ = 446624640.

The previous prime is 688925603. The next prime is 688925669. The reversal of 688925661 is 166529886.

It is a de Polignac number, because none of the positive numbers 2^k-688925661 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688925669) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17881 + ... + 41201.

It is an arithmetic number, because the mean of its divisors is an integer number (59004660).

Almost surely, 2^688925661 is an apocalyptic number.

It is an amenable number.

688925661 is a deficient number, since it is larger than the sum of its proper divisors (255148899).

688925661 is a wasteful number, since it uses less digits than its factorization.

688925661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23596.

The product of its digits is 1244160, while the sum is 51.

The square root of 688925661 is about 26247.3934134420. The cubic root of 688925661 is about 883.1967329136.

The spelling of 688925661 in words is "six hundred eighty-eight million, nine hundred twenty-five thousand, six hundred sixty-one".