1221120100021 has 2 divisors, whose sum is σ = 1221120100022. Its totient is φ = 1221120100020.

The previous prime is 1221120100009. The next prime is 1221120100073. The reversal of 1221120100021 is 1200010211221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 620882537521 + 600237562500 = 787961^2 + 774750^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221120100021 - 2¹⁵ = 1221120067253 is a prime.

It is a super-2 number, since 2×1221120100021² (a number of 25 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1221120099974 and 1221120100010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221120100001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610560050010 + 610560050011.

It is an arithmetic number, because the mean of its divisors is an integer number (610560050011).

Almost surely, 2^{1221120100021} is an apocalyptic number.

It is an amenable number.

1221120100021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221120100021 is an equidigital number, since it uses as much as digits as its factorization.

1221120100021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 1221120100021 its reverse (1200010211221), we get a palindrome (2421130311242).

The spelling of 1221120100021 in words is "one trillion, two hundred twenty-one billion, one hundred twenty million, one hundred thousand, twenty-one".