1221100011721 has 2 divisors, whose sum is σ = 1221100011722. Its totient is φ = 1221100011720.

The previous prime is 1221100011707. The next prime is 1221100011763. The reversal of 1221100011721 is 1271100011221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 757422090000 + 463677921721 = 870300^2 + 680939^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221100011721 - 2⁵ = 1221100011689 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221100611721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610550005860 + 610550005861.

It is an arithmetic number, because the mean of its divisors is an integer number (610550005861).

Almost surely, 2^{1221100011721} is an apocalyptic number.

It is an amenable number.

1221100011721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221100011721 is an equidigital number, since it uses as much as digits as its factorization.

1221100011721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 56, while the sum is 19.

Adding to 1221100011721 its reverse (1271100011221), we get a palindrome (2492200022942).

The spelling of 1221100011721 in words is "one trillion, two hundred twenty-one billion, one hundred million, eleven thousand, seven hundred twenty-one".