21556933 has 2 divisors, whose sum is σ = 21556934. Its totient is φ = 21556932.

The previous prime is 21556921. The next prime is 21556937. The reversal of 21556933 is 33965512.

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., 11175649 + 10381284 = 3343^2 + 3222^2 .

It is a cyclic number.

It is not a de Polignac number, because 21556933 - 2⁹ = 21556421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21556937) by changing a digit.

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

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10778466 + 10778467.

It is an arithmetic number, because the mean of its divisors is an integer number (10778467).

Almost surely, 2^21556933 is an apocalyptic number.

It is an amenable number.

21556933 is a deficient number, since it is larger than the sum of its proper divisors (1).

21556933 is an equidigital number, since it uses as much as digits as its factorization.

21556933 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24300, while the sum is 34.

The square root of 21556933 is about 4642.9444321465. The cubic root of 21556933 is about 278.3101149153.

The spelling of 21556933 in words is "twenty-one million, five hundred fifty-six thousand, nine hundred thirty-three".