21866113 has 2 divisors, whose sum is σ = 21866114. Its totient is φ = 21866112.

The previous prime is 21866111. The next prime is 21866137. The reversal of 21866113 is 31166812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20142144 + 1723969 = 4488^2 + 1313^2 .

It is a cyclic number.

It is not a de Polignac number, because 21866113 - 2¹ = 21866111 is a prime.

Together with 21866111, it forms a pair of twin primes.

It is equal to p_1381294 and since 21866113 and 1381294 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21866111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10933056 + 10933057.

It is an arithmetic number, because the mean of its divisors is an integer number (10933057).

Almost surely, 2^21866113 is an apocalyptic number.

It is an amenable number.

21866113 is a deficient number, since it is larger than the sum of its proper divisors (1).

21866113 is an equidigital number, since it uses as much as digits as its factorization.

21866113 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1728, while the sum is 28.

The square root of 21866113 is about 4676.1215766915. The cubic root of 21866113 is about 279.6343569098.

The spelling of 21866113 in words is "twenty-one million, eight hundred sixty-six thousand, one hundred thirteen".