20669556679 has 4 divisors (see below), whose sum is σ = 21228193384. Its totient is φ = 20110919976.

The previous prime is 20669556637. The next prime is 20669556701. The reversal of 20669556679 is 97665596602.

It is a happy number.

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 20669556679 - 2²³ = 20661168071 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20669554679) 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, 279318297 + ... + 279318370.

It is an arithmetic number, because the mean of its divisors is an integer number (5307048346).

Almost surely, 2^20669556679 is an apocalyptic number.

20669556679 is a deficient number, since it is larger than the sum of its proper divisors (558636705).

20669556679 is an equidigital number, since it uses as much as digits as its factorization.

20669556679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 558636704.

The product of its (nonzero) digits is 36741600, while the sum is 61.

The spelling of 20669556679 in words is "twenty billion, six hundred sixty-nine million, five hundred fifty-six thousand, six hundred seventy-nine".