21911837 has 2 divisors, whose sum is σ = 21911838. Its totient is φ = 21911836.

The previous prime is 21911819. The next prime is 21911839. The reversal of 21911837 is 73811912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18887716 + 3024121 = 4346^2 + 1739^2 .

It is a cyclic number.

It is not a de Polignac number, because 21911837 - 2⁸ = 21911581 is a prime.

Together with 21911839, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21911839) 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, 10955918 + 10955919.

It is an arithmetic number, because the mean of its divisors is an integer number (10955919).

Almost surely, 2^21911837 is an apocalyptic number.

It is an amenable number.

21911837 is a deficient number, since it is larger than the sum of its proper divisors (1).

21911837 is an equidigital number, since it uses as much as digits as its factorization.

21911837 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 32.

The square root of 21911837 is about 4681.0081179165. The cubic root of 21911837 is about 279.8291346991.

The spelling of 21911837 in words is "twenty-one million, nine hundred eleven thousand, eight hundred thirty-seven".