21423271 has 2 divisors, whose sum is σ = 21423272. Its totient is φ = 21423270.

The previous prime is 21423251. The next prime is 21423287. The reversal of 21423271 is 17232412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21423271 - 2⁵ = 21423239 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21423221) 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, 10711635 + 10711636.

It is an arithmetic number, because the mean of its divisors is an integer number (10711636).

Almost surely, 2^21423271 is an apocalyptic number.

21423271 is a deficient number, since it is larger than the sum of its proper divisors (1).

21423271 is an equidigital number, since it uses as much as digits as its factorization.

21423271 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 672, while the sum is 22.

The square root of 21423271 is about 4628.5279517358. The cubic root of 21423271 is about 277.7337089141.

Adding to 21423271 its reverse (17232412), we get a palindrome (38655683).

The spelling of 21423271 in words is "twenty-one million, four hundred twenty-three thousand, two hundred seventy-one".