1221111221021 has 2 divisors, whose sum is σ = 1221111221022. Its totient is φ = 1221111221020.

The previous prime is 1221111221017. The next prime is 1221111221131. The reversal of 1221111221021 is 1201221111221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 631049116996 + 590062104025 = 794386^2 + 768155^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221111221021 - 2² = 1221111221017 is a prime.

It is a super-2 number, since 2×1221111221021² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221111221621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610555610510 + 610555610511.

It is an arithmetic number, because the mean of its divisors is an integer number (610555610511).

Almost surely, 2^{1221111221021} is an apocalyptic number.

It is an amenable number.

1221111221021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221111221021 is an equidigital number, since it uses as much as digits as its factorization.

1221111221021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 1221111221021 its reverse (1201221111221), we get a palindrome (2422332332242).

The spelling of 1221111221021 in words is "one trillion, two hundred twenty-one billion, one hundred eleven million, two hundred twenty-one thousand, twenty-one".