21121211 has 2 divisors, whose sum is σ = 21121212. Its totient is φ = 21121210.

The previous prime is 21121207. The next prime is 21121223. The reversal of 21121211 is 11212112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21121211 - 2² = 21121207 is a prime.

It is a super-2 number, since 2×21121211² = 892211108213042, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21121192 and 21121201.

It is not a weakly prime, because it can be changed into another prime (21121201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560605 + 10560606.

It is an arithmetic number, because the mean of its divisors is an integer number (10560606).

Almost surely, 2^21121211 is an apocalyptic number.

21121211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121211 is an equidigital number, since it uses as much as digits as its factorization.

21121211 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8, while the sum is 11.

The square root of 21121211 is about 4595.7818703677. The cubic root of 21121211 is about 276.4222122576.

Adding to 21121211 its reverse (11212112), we get a palindrome (32333323).

Subtracting from 21121211 its reverse (11212112), we obtain a palindrome (9909099).

It can be divided in two parts, 2 and 1121211, that multiplied together give a palindrome (2242422).

The spelling of 21121211 in words is "twenty-one million, one hundred twenty-one thousand, two hundred eleven".