21897223 has 2 divisors, whose sum is σ = 21897224. Its totient is φ = 21897222.

The previous prime is 21897193. The next prime is 21897247. The reversal of 21897223 is 32279812.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21897223 is a prime.

It is a super-2 number, since 2×21897223² = 958976750223458, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21897283) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10948611 + 10948612.

It is an arithmetic number, because the mean of its divisors is an integer number (10948612).

Almost surely, 2^21897223 is an apocalyptic number.

21897223 is a deficient number, since it is larger than the sum of its proper divisors (1).

21897223 is an equidigital number, since it uses as much as digits as its factorization.

21897223 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12096, while the sum is 34.

The square root of 21897223 is about 4679.4468690220. The cubic root of 21897223 is about 279.7669106076.

The spelling of 21897223 in words is "twenty-one million, eight hundred ninety-seven thousand, two hundred twenty-three".