21543611 has 2 divisors, whose sum is σ = 21543612. Its totient is φ = 21543610.

The previous prime is 21543593. The next prime is 21543619. The reversal of 21543611 is 11634512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21543611 - 2¹⁴ = 21527227 is a prime.

It is not a weakly prime, because it can be changed into another prime (21543619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10771805 + 10771806.

It is an arithmetic number, because the mean of its divisors is an integer number (10771806).

Almost surely, 2^21543611 is an apocalyptic number.

21543611 is a deficient number, since it is larger than the sum of its proper divisors (1).

21543611 is an equidigital number, since it uses as much as digits as its factorization.

21543611 is an evil number, because the sum of its binary digits is even.

The product of its digits is 720, while the sum is 23.

The square root of 21543611 is about 4641.5095604771. The cubic root of 21543611 is about 278.2527720119.

Subtracting from 21543611 its reverse (11634512), we obtain a palindrome (9909099).

The spelling of 21543611 in words is "twenty-one million, five hundred forty-three thousand, six hundred eleven".