21243611 has 2 divisors, whose sum is σ = 21243612. Its totient is φ = 21243610.

The previous prime is 21243589. The next prime is 21243637. The reversal of 21243611 is 11634212.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21243611 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21243011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621805 + 10621806.

It is an arithmetic number, because the mean of its divisors is an integer number (10621806).

Almost surely, 2^21243611 is an apocalyptic number.

21243611 is a deficient number, since it is larger than the sum of its proper divisors (1).

21243611 is an equidigital number, since it uses as much as digits as its factorization.

21243611 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 20.

The square root of 21243611 is about 4609.0791922031. The cubic root of 21243611 is about 276.9551509363.

Adding to 21243611 its reverse (11634212), we get a palindrome (32877823).

The spelling of 21243611 in words is "twenty-one million, two hundred forty-three thousand, six hundred eleven".