1221111002021 has 2 divisors, whose sum is σ = 1221111002022. Its totient is φ = 1221111002020.

The previous prime is 1221111001991. The next prime is 1221111002039. The reversal of 1221111002021 is 1202001111221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1028490081025 + 192620920996 = 1014145^2 + 438886^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221111002021 is a prime.

It is a super-2 number, since 2×1221111002021² (a number of 25 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1221111001987 and 1221111002005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221111002051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610555501010 + 610555501011.

It is an arithmetic number, because the mean of its divisors is an integer number (610555501011).

Almost surely, 2^{1221111002021} is an apocalyptic number.

It is an amenable number.

1221111002021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221111002021 is an equidigital number, since it uses as much as digits as its factorization.

1221111002021 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 14.

Adding to 1221111002021 its reverse (1202001111221), we get a palindrome (2423112113242).

The spelling of 1221111002021 in words is "one trillion, two hundred twenty-one billion, one hundred eleven million, two thousand, twenty-one".