20865458721 has 8 divisors (see below), whose sum is σ = 27845838720. Its totient is φ = 13897692272.

The previous prime is 20865458693. The next prime is 20865458723. The reversal of 20865458721 is 12785456802.

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

It is a cyclic number.

It is not a de Polignac number, because 20865458721 - 2⁵ = 20865458689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20865458723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3149526 + ... + 3156143.

It is an arithmetic number, because the mean of its divisors is an integer number (3480729840).

Almost surely, 2^20865458721 is an apocalyptic number.

It is an amenable number.

20865458721 is a deficient number, since it is larger than the sum of its proper divisors (6980379999).

20865458721 is a wasteful number, since it uses less digits than its factorization.

20865458721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6306775.

The product of its (nonzero) digits is 1075200, while the sum is 48.

The spelling of 20865458721 in words is "twenty billion, eight hundred sixty-five million, four hundred fifty-eight thousand, seven hundred twenty-one".