21022091 has 2 divisors, whose sum is σ = 21022092. Its totient is φ = 21022090.

The previous prime is 21022063. The next prime is 21022093. The reversal of 21022091 is 19022012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21022091 - 2¹⁰ = 21021067 is a prime.

It is a Sophie Germain prime.

Together with 21022093, 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 (21022093) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10511045 + 10511046.

It is an arithmetic number, because the mean of its divisors is an integer number (10511046).

Almost surely, 2^21022091 is an apocalyptic number.

21022091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21022091 is an equidigital number, since it uses as much as digits as its factorization.

21022091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21022091 is about 4584.9853871087. The cubic root of 21022091 is about 275.9891256305.

The spelling of 21022091 in words is "twenty-one million, twenty-two thousand, ninety-one".