21806023 has 2 divisors, whose sum is σ = 21806024. Its totient is φ = 21806022.

The previous prime is 21806011. The next prime is 21806041. The reversal of 21806023 is 32060812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21806023 - 2⁵ = 21805991 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21805985 and 21806003.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21806003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10903011 + 10903012.

It is an arithmetic number, because the mean of its divisors is an integer number (10903012).

Almost surely, 2^21806023 is an apocalyptic number.

21806023 is a deficient number, since it is larger than the sum of its proper divisors (1).

21806023 is an equidigital number, since it uses as much as digits as its factorization.

21806023 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 21806023 is about 4669.6919598620. The cubic root of 21806023 is about 279.3779686452.

Adding to 21806023 its reverse (32060812), we get a palindrome (53866835).

The spelling of 21806023 in words is "twenty-one million, eight hundred six thousand, twenty-three".