21543271 has 2 divisors, whose sum is σ = 21543272. Its totient is φ = 21543270.

The previous prime is 21543241. The next prime is 21543289. The reversal of 21543271 is 17234512.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21543271 is a prime.

It is a super-2 number, since 2×21543271² = 928225050758882, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21543211) 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, 10771635 + 10771636.

It is an arithmetic number, because the mean of its divisors is an integer number (10771636).

Almost surely, 2^21543271 is an apocalyptic number.

21543271 is a deficient number, since it is larger than the sum of its proper divisors (1).

21543271 is an equidigital number, since it uses as much as digits as its factorization.

21543271 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1680, while the sum is 25.

The square root of 21543271 is about 4641.4729343173. The cubic root of 21543271 is about 278.2513082146.

Adding to 21543271 its reverse (17234512), we get a palindrome (38777783).

The spelling of 21543271 in words is "twenty-one million, five hundred forty-three thousand, two hundred seventy-one".