20688668617 has 4 divisors (see below), whose sum is σ = 21356045056. Its totient is φ = 20021292180.

The previous prime is 20688668569. The next prime is 20688668621. The reversal of 20688668617 is 71686688602.

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 20688668617 - 2⁷ = 20688668489 is a prime.

It is a super-3 number, since 3×20688668617³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20688668417) 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, 333688173 + ... + 333688234.

It is an arithmetic number, because the mean of its divisors is an integer number (5339011264).

Almost surely, 2^20688668617 is an apocalyptic number.

It is an amenable number.

20688668617 is a deficient number, since it is larger than the sum of its proper divisors (667376439).

20688668617 is an equidigital number, since it uses as much as digits as its factorization.

20688668617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 667376438.

The product of its (nonzero) digits is 9289728, while the sum is 58.

The spelling of 20688668617 in words is "twenty billion, six hundred eighty-eight million, six hundred sixty-eight thousand, six hundred seventeen".