21271843 has 2 divisors, whose sum is σ = 21271844. Its totient is φ = 21271842.

The previous prime is 21271841. The next prime is 21271883. The reversal of 21271843 is 34817212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21271843 - 2¹ = 21271841 is a prime.

Together with 21271841, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21271841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10635921 + 10635922.

It is an arithmetic number, because the mean of its divisors is an integer number (10635922).

Almost surely, 2^21271843 is an apocalyptic number.

21271843 is a deficient number, since it is larger than the sum of its proper divisors (1).

21271843 is an equidigital number, since it uses as much as digits as its factorization.

21271843 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2688, while the sum is 28.

The square root of 21271843 is about 4612.1408261240. The cubic root of 21271843 is about 277.0777844606.

The spelling of 21271843 in words is "twenty-one million, two hundred seventy-one thousand, eight hundred forty-three".