12221221981 has 2 divisors, whose sum is σ = 12221221982. Its totient is φ = 12221221980.

The previous prime is 12221221973. The next prime is 12221222011. The reversal of 12221221981 is 18912212221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10065105625 + 2156116356 = 100325^2 + 46434^2 .

It is a cyclic number.

It is not a de Polignac number, because 12221221981 - 2³ = 12221221973 is a prime.

It is a super-2 number, since 2×12221221981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12221221931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6110610990 + 6110610991.

It is an arithmetic number, because the mean of its divisors is an integer number (6110610991).

Almost surely, 2^12221221981 is an apocalyptic number.

It is an amenable number.

12221221981 is a deficient number, since it is larger than the sum of its proper divisors (1).

12221221981 is an equidigital number, since it uses as much as digits as its factorization.

12221221981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2304, while the sum is 31.

The spelling of 12221221981 in words is "twelve billion, two hundred twenty-one million, two hundred twenty-one thousand, nine hundred eighty-one".