1221202021121 has 2 divisors, whose sum is σ = 1221202021122. Its totient is φ = 1221202021120.

The previous prime is 1221202021111. The next prime is 1221202021133. The reversal of 1221202021121 is 1211202021221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 653154912400 + 568047108721 = 808180^2 + 753689^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221202021121 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1221202021121.

It is not a weakly prime, because it can be changed into another prime (1221202021111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610601010560 + 610601010561.

It is an arithmetic number, because the mean of its divisors is an integer number (610601010561).

Almost surely, 2^{1221202021121} is an apocalyptic number.

It is an amenable number.

1221202021121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221202021121 is an equidigital number, since it uses as much as digits as its factorization.

1221202021121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 1221202021121 its reverse (1211202021221), we get a palindrome (2432404042342).

The spelling of 1221202021121 in words is "one trillion, two hundred twenty-one billion, two hundred two million, twenty-one thousand, one hundred twenty-one".