1231221111221 has 2 divisors, whose sum is σ = 1231221111222. Its totient is φ = 1231221111220.

The previous prime is 1231221111191. The next prime is 1231221111229. The reversal of 1231221111221 is 1221111221321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 962704380625 + 268516730596 = 981175^2 + 518186^2 .

It is a cyclic number.

It is not a de Polignac number, because 1231221111221 - 2¹⁴ = 1231221094837 is a prime.

It is a super-2 number, since 2×1231221111221² (a number of 25 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1231221111193 and 1231221111202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1231221111229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615610555610 + 615610555611.

It is an arithmetic number, because the mean of its divisors is an integer number (615610555611).

Almost surely, 2^{1231221111221} is an apocalyptic number.

It is an amenable number.

1231221111221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231221111221 is an equidigital number, since it uses as much as digits as its factorization.

1231221111221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 96, while the sum is 20.

Adding to 1231221111221 its reverse (1221111221321), we get a palindrome (2452332332542).

The spelling of 1231221111221 in words is "one trillion, two hundred thirty-one billion, two hundred twenty-one million, one hundred eleven thousand, two hundred twenty-one".