20656666509 has 8 divisors (see below), whose sum is σ = 27568888512. Its totient is φ = 13757777760.

The previous prime is 20656666501. The next prime is 20656666517. The reversal of 20656666509 is 90566665602.

It is an interprime number because it is at equal distance from previous prime (20656666501) and next prime (20656666517).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20656666509 - 2³ = 20656666501 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20656666501) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3329697 + ... + 3335894.

It is an arithmetic number, because the mean of its divisors is an integer number (3446111064).

Almost surely, 2^20656666509 is an apocalyptic number.

It is an amenable number.

20656666509 is a deficient number, since it is larger than the sum of its proper divisors (6912222003).

20656666509 is a wasteful number, since it uses less digits than its factorization.

20656666509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6666627.

The product of its (nonzero) digits is 3499200, while the sum is 51.

The spelling of 20656666509 in words is "twenty billion, six hundred fifty-six million, six hundred sixty-six thousand, five hundred nine".