21417271 has 2 divisors, whose sum is σ = 21417272. Its totient is φ = 21417270.

The previous prime is 21417269. The next prime is 21417299. The reversal of 21417271 is 17271412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21417271 - 2¹ = 21417269 is a prime.

Together with 21417269, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21417371) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10708635 + 10708636.

It is an arithmetic number, because the mean of its divisors is an integer number (10708636).

Almost surely, 2^21417271 is an apocalyptic number.

21417271 is a deficient number, since it is larger than the sum of its proper divisors (1).

21417271 is an equidigital number, since it uses as much as digits as its factorization.

21417271 is an evil number, because the sum of its binary digits is even.

The product of its digits is 784, while the sum is 25.

The square root of 21417271 is about 4627.8797521111. The cubic root of 21417271 is about 277.7077782669.

Adding to 21417271 its reverse (17271412), we get a palindrome (38688683).

The spelling of 21417271 in words is "twenty-one million, four hundred seventeen thousand, two hundred seventy-one".