221210011611521 has 2 divisors, whose sum is σ = 221210011611522. Its totient is φ = 221210011611520.

The previous prime is 221210011611437. The next prime is 221210011611559. The reversal of 221210011611521 is 125116110012122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 199025393508496 + 22184618103025 = 14107636^2 + 4710055^2 .

It is a cyclic number.

It is not a de Polignac number, because 221210011611521 - 2³⁰ = 221208937869697 is a prime.

It is not a weakly prime, because it can be changed into another prime (221210011611571) 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, 110605005805760 + 110605005805761.

It is an arithmetic number, because the mean of its divisors is an integer number (110605005805761).

Almost surely, 2^{221210011611521} is an apocalyptic number.

It is an amenable number.

221210011611521 is a deficient number, since it is larger than the sum of its proper divisors (1).

221210011611521 is an equidigital number, since it uses as much as digits as its factorization.

221210011611521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 26.

Adding to 221210011611521 its reverse (125116110012122), we get a palindrome (346326121623643).

The spelling of 221210011611521 in words is "two hundred twenty-one trillion, two hundred ten billion, eleven million, six hundred eleven thousand, five hundred twenty-one".