21221171 has 2 divisors, whose sum is σ = 21221172. Its totient is φ = 21221170.

The previous prime is 21221153. The next prime is 21221237. The reversal of 21221171 is 17112212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21221171 - 2¹⁴ = 21204787 is a prime.

It is a super-2 number, since 2×21221171² = 900676197222482, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21221131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610585 + 10610586.

It is an arithmetic number, because the mean of its divisors is an integer number (10610586).

Almost surely, 2^21221171 is an apocalyptic number.

21221171 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221171 is an equidigital number, since it uses as much as digits as its factorization.

21221171 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56, while the sum is 17.

The square root of 21221171 is about 4606.6442232931. The cubic root of 21221171 is about 276.8575990471.

Adding to 21221171 its reverse (17112212), we get a palindrome (38333383).

The spelling of 21221171 in words is "twenty-one million, two hundred twenty-one thousand, one hundred seventy-one".