20688668591 has 4 divisors (see below), whose sum is σ = 20878473000. Its totient is φ = 20498864184.

The previous prime is 20688668569. The next prime is 20688668621. The reversal of 20688668591 is 19586688602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20688668591 - 2¹⁰ = 20688667567 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20688668591.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20688668501) 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, 94902041 + ... + 94902258.

It is an arithmetic number, because the mean of its divisors is an integer number (5219618250).

Almost surely, 2^20688668591 is an apocalyptic number.

20688668591 is a deficient number, since it is larger than the sum of its proper divisors (189804409).

20688668591 is a wasteful number, since it uses less digits than its factorization.

20688668591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189804408.

The product of its (nonzero) digits is 9953280, while the sum is 59.

The spelling of 20688668591 in words is "twenty billion, six hundred eighty-eight million, six hundred sixty-eight thousand, five hundred ninety-one".