1221002120981 has 2 divisors, whose sum is σ = 1221002120982. Its totient is φ = 1221002120980.

The previous prime is 1221002120893. The next prime is 1221002121041. The reversal of 1221002120981 is 1890212001221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 624337022500 + 596665098481 = 790150^2 + 772441^2 .

It is an emirp because it is prime and its reverse (1890212001221) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1221002120981 - 2¹⁰ = 1221002119957 is a prime.

It is a super-2 number, since 2×1221002120981² (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 (1221002150981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610501060490 + 610501060491.

It is an arithmetic number, because the mean of its divisors is an integer number (610501060491).

Almost surely, 2^{1221002120981} is an apocalyptic number.

It is an amenable number.

1221002120981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221002120981 is an equidigital number, since it uses as much as digits as its factorization.

1221002120981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 29.

The spelling of 1221002120981 in words is "one trillion, two hundred twenty-one billion, two million, one hundred twenty thousand, nine hundred eighty-one".