12211981 has 2 divisors, whose sum is σ = 12211982. Its totient is φ = 12211980.

The previous prime is 12211949. The next prime is 12212021. The reversal of 12211981 is 18911221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9180900 + 3031081 = 3030^2 + 1741^2 .

It is a cyclic number.

It is not a de Polignac number, because 12211981 - 2⁵ = 12211949 is a prime.

It is a super-2 number, since 2×12211981² = 298264959888722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12214981) 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, 6105990 + 6105991.

It is an arithmetic number, because the mean of its divisors is an integer number (6105991).

Almost surely, 2^12211981 is an apocalyptic number.

It is an amenable number.

12211981 is a deficient number, since it is larger than the sum of its proper divisors (1).

12211981 is an equidigital number, since it uses as much as digits as its factorization.

12211981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 288, while the sum is 25.

The square root of 12211981 is about 3494.5644936100. The cubic root of 12211981 is about 230.2830855859.

The spelling of 12211981 in words is "twelve million, two hundred eleven thousand, nine hundred eighty-one".