21223841 has 2 divisors, whose sum is σ = 21223842. Its totient is φ = 21223840.

The previous prime is 21223823. The next prime is 21223843. The reversal of 21223841 is 14832212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12103441 + 9120400 = 3479^2 + 3020^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21223841 is a prime.

Together with 21223843, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21223843) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10611920 + 10611921.

It is an arithmetic number, because the mean of its divisors is an integer number (10611921).

Almost surely, 2^21223841 is an apocalyptic number.

It is an amenable number.

21223841 is a deficient number, since it is larger than the sum of its proper divisors (1).

21223841 is an equidigital number, since it uses as much as digits as its factorization.

21223841 is an evil number, because the sum of its binary digits is even.

The product of its digits is 768, while the sum is 23.

The square root of 21223841 is about 4606.9340129852. The cubic root of 21223841 is about 276.8692097602.

The spelling of 21223841 in words is "twenty-one million, two hundred twenty-three thousand, eight hundred forty-one".