20665567021 has 8 divisors (see below), whose sum is σ = 22553946144. Its totient is φ = 18778803120.

The previous prime is 20665567009. The next prime is 20665567031. The reversal of 20665567021 is 12076556602.

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

It is not a de Polignac number, because 20665567021 - 2⁷ = 20665566893 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 (20665567001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 376971 + ... + 428296.

It is an arithmetic number, because the mean of its divisors is an integer number (2819243268).

Almost surely, 2^20665567021 is an apocalyptic number.

It is an amenable number.

20665567021 is a deficient number, since it is larger than the sum of its proper divisors (1888379123).

20665567021 is a wasteful number, since it uses less digits than its factorization.

20665567021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 807611.

The product of its (nonzero) digits is 151200, while the sum is 40.

The spelling of 20665567021 in words is "twenty billion, six hundred sixty-five million, five hundred sixty-seven thousand, twenty-one".