688566561 has 4 divisors (see below), whose sum is σ = 918088752. Its totient is φ = 459044372.

The previous prime is 688566533. The next prime is 688566577. The reversal of 688566561 is 165665886.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 688566561 - 2¹³ = 688558369 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (688566511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 114761091 + ... + 114761096.

It is an arithmetic number, because the mean of its divisors is an integer number (229522188).

Almost surely, 2^688566561 is an apocalyptic number.

It is an amenable number.

688566561 is a deficient number, since it is larger than the sum of its proper divisors (229522191).

688566561 is a wasteful number, since it uses less digits than its factorization.

688566561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 229522190.

The product of its digits is 2073600, while the sum is 51.

The square root of 688566561 is about 26240.5518425204. The cubic root of 688566561 is about 883.0432518796.

The spelling of 688566561 in words is "six hundred eighty-eight million, five hundred sixty-six thousand, five hundred sixty-one".