21254221 has 2 divisors, whose sum is σ = 21254222. Its totient is φ = 21254220.

The previous prime is 21254213. The next prime is 21254227. The reversal of 21254221 is 12245212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12320100 + 8934121 = 3510^2 + 2989^2 .

It is a cyclic number.

It is not a de Polignac number, because 21254221 - 2³ = 21254213 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21254227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627110 + 10627111.

It is an arithmetic number, because the mean of its divisors is an integer number (10627111).

Almost surely, 2^21254221 is an apocalyptic number.

It is an amenable number.

21254221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21254221 is an equidigital number, since it uses as much as digits as its factorization.

21254221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 320, while the sum is 19.

The square root of 21254221 is about 4610.2300376445. The cubic root of 21254221 is about 277.0012511510.

Adding to 21254221 its reverse (12245212), we get a palindrome (33499433).

Subtracting from 21254221 its reverse (12245212), we obtain a palindrome (9009009).

The spelling of 21254221 in words is "twenty-one million, two hundred fifty-four thousand, two hundred twenty-one".