1221513052021 has 2 divisors, whose sum is σ = 1221513052022. Its totient is φ = 1221513052020.

The previous prime is 1221513051881. The next prime is 1221513052033. The reversal of 1221513052021 is 1202503151221.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 837719172900 + 383793879121 = 915270^2 + 619511^2 .

It is an emirp because it is prime and its reverse (1202503151221) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1221513052021 - 2³⁹ = 671757238133 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221513052121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610756526010 + 610756526011.

It is an arithmetic number, because the mean of its divisors is an integer number (610756526011).

Almost surely, 2^{1221513052021} is an apocalyptic number.

It is an amenable number.

1221513052021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221513052021 is an equidigital number, since it uses as much as digits as its factorization.

1221513052021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1200, while the sum is 25.

The spelling of 1221513052021 in words is "one trillion, two hundred twenty-one billion, five hundred thirteen million, fifty-two thousand, twenty-one".