21026171 has 2 divisors, whose sum is σ = 21026172. Its totient is φ = 21026170.

The previous prime is 21026149. The next prime is 21026191. The reversal of 21026171 is 17162012.

It is an a-pointer prime, because the next prime (21026191) can be obtained adding 21026171 to its sum of digits (20).

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21026171 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21026191) 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, 10513085 + 10513086.

It is an arithmetic number, because the mean of its divisors is an integer number (10513086).

Almost surely, 2^21026171 is an apocalyptic number.

21026171 is a deficient number, since it is larger than the sum of its proper divisors (1).

21026171 is an equidigital number, since it uses as much as digits as its factorization.

21026171 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 168, while the sum is 20.

The square root of 21026171 is about 4585.4302960573. The cubic root of 21026171 is about 276.0069792746.

Adding to 21026171 its reverse (17162012), we get a palindrome (38188183).

The spelling of 21026171 in words is "twenty-one million, twenty-six thousand, one hundred seventy-one".