21667271 has 2 divisors, whose sum is σ = 21667272. Its totient is φ = 21667270.

The previous prime is 21667253. The next prime is 21667273. The reversal of 21667271 is 17276612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21667271 - 2⁶ = 21667207 is a prime.

Together with 21667273, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21667273) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10833635 + 10833636.

It is an arithmetic number, because the mean of its divisors is an integer number (10833636).

Almost surely, 2^21667271 is an apocalyptic number.

21667271 is a deficient number, since it is larger than the sum of its proper divisors (1).

21667271 is an equidigital number, since it uses as much as digits as its factorization.

21667271 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7056, while the sum is 32.

The square root of 21667271 is about 4654.8115966170. The cubic root of 21667271 is about 278.7841455085.

The spelling of 21667271 in words is "twenty-one million, six hundred sixty-seven thousand, two hundred seventy-one".