21806715817 has 16 divisors (see below), whose sum is σ = 23084328960. Its totient is φ = 20558577600.

The previous prime is 21806715781. The next prime is 21806715829. The reversal of 21806715817 is 71851760812.

It is not a de Polignac number, because 21806715817 - 2²³ = 21798327209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21806745817) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 456067 + ... + 501607.

It is an arithmetic number, because the mean of its divisors is an integer number (1442770560).

Almost surely, 2^21806715817 is an apocalyptic number.

It is an amenable number.

21806715817 is a deficient number, since it is larger than the sum of its proper divisors (1277613143).

21806715817 is a wasteful number, since it uses less digits than its factorization.

21806715817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45864.

The product of its (nonzero) digits is 188160, while the sum is 46.

The spelling of 21806715817 in words is "twenty-one billion, eight hundred six million, seven hundred fifteen thousand, eight hundred seventeen".