21121171 has 2 divisors, whose sum is σ = 21121172. Its totient is φ = 21121170.

The previous prime is 21121129. The next prime is 21121187. The reversal of 21121171 is 17112112.

It is an a-pointer prime, because the next prime (21121187) can be obtained adding 21121171 to its sum of digits (16).

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21121171 - 2¹³ = 21112979 is a prime.

It is a super-2 number, since 2×21121171² = 892207728822482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21121271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560585 + 10560586.

It is an arithmetic number, because the mean of its divisors is an integer number (10560586).

Almost surely, 2^21121171 is an apocalyptic number.

21121171 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121171 is an equidigital number, since it uses as much as digits as its factorization.

21121171 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 28, while the sum is 16.

The square root of 21121171 is about 4595.7775185490. Note that the first 3 decimals coincide. The cubic root of 21121171 is about 276.4220377586.

Adding to 21121171 its reverse (17112112), we get a palindrome (38233283).

The spelling of 21121171 in words is "twenty-one million, one hundred twenty-one thousand, one hundred seventy-one".