21723211 has 2 divisors, whose sum is σ = 21723212. Its totient is φ = 21723210.

The previous prime is 21723203. The next prime is 21723227. The reversal of 21723211 is 11232712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21723211 - 2³ = 21723203 is a prime.

It is not a weakly prime, because it can be changed into another prime (21723271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10861605 + 10861606.

It is an arithmetic number, because the mean of its divisors is an integer number (10861606).

Almost surely, 2^21723211 is an apocalyptic number.

21723211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21723211 is an equidigital number, since it uses as much as digits as its factorization.

21723211 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 168, while the sum is 19.

The square root of 21723211 is about 4660.8165593595. The cubic root of 21723211 is about 279.0238585644.

Adding to 21723211 its reverse (11232712), we get a palindrome (32955923).

The spelling of 21723211 in words is "twenty-one million, seven hundred twenty-three thousand, two hundred eleven".