1221310201921 has 2 divisors, whose sum is σ = 1221310201922. Its totient is φ = 1221310201920.

The previous prime is 1221310201889. The next prime is 1221310201933. The reversal of 1221310201921 is 1291020131221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1025083351296 + 196226850625 = 1012464^2 + 442975^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221310201921 - 2⁵ = 1221310201889 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221310201961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610655100960 + 610655100961.

It is an arithmetic number, because the mean of its divisors is an integer number (610655100961).

Almost surely, 2^{1221310201921} is an apocalyptic number.

It is an amenable number.

1221310201921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221310201921 is an equidigital number, since it uses as much as digits as its factorization.

1221310201921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 25.

The spelling of 1221310201921 in words is "one trillion, two hundred twenty-one billion, three hundred ten million, two hundred one thousand, nine hundred twenty-one".