21894571 has 2 divisors, whose sum is σ = 21894572. Its totient is φ = 21894570.

The previous prime is 21894569. The next prime is 21894581. The reversal of 21894571 is 17549812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21894571 - 2¹ = 21894569 is a prime.

Together with 21894569, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21894571.

It is not a weakly prime, because it can be changed into another prime (21894511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10947285 + 10947286.

It is an arithmetic number, because the mean of its divisors is an integer number (10947286).

Almost surely, 2^21894571 is an apocalyptic number.

21894571 is a deficient number, since it is larger than the sum of its proper divisors (1).

21894571 is an equidigital number, since it uses as much as digits as its factorization.

21894571 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 37.

The square root of 21894571 is about 4679.1634936172. The cubic root of 21894571 is about 279.7556158451.

The spelling of 21894571 in words is "twenty-one million, eight hundred ninety-four thousand, five hundred seventy-one".