21807855793 has 2 divisors, whose sum is σ = 21807855794. Its totient is φ = 21807855792.

The previous prime is 21807855767. The next prime is 21807855809. The reversal of 21807855793 is 39755870812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20907135649 + 900720144 = 144593^2 + 30012^2 .

It is a cyclic number.

It is not a de Polignac number, because 21807855793 - 2³³ = 13217921201 is a prime.

It is not a weakly prime, because it can be changed into another prime (21807855733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10903927896 + 10903927897.

It is an arithmetic number, because the mean of its divisors is an integer number (10903927897).

Almost surely, 2^21807855793 is an apocalyptic number.

It is an amenable number.

21807855793 is a deficient number, since it is larger than the sum of its proper divisors (1).

21807855793 is an equidigital number, since it uses as much as digits as its factorization.

21807855793 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4233600, while the sum is 55.

The spelling of 21807855793 in words is "twenty-one billion, eight hundred seven million, eight hundred fifty-five thousand, seven hundred ninety-three".