21120120220981 has 2 divisors, whose sum is σ = 21120120220982. Its totient is φ = 21120120220980.

The previous prime is 21120120220973. The next prime is 21120120221003. The reversal of 21120120220981 is 18902202102112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14218623436081 + 6901496784900 = 3770759^2 + 2627070^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120120220981 - 2³ = 21120120220973 is a prime.

It is a super-2 number, since 2×21120120220981² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21120120290981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560060110490 + 10560060110491.

It is an arithmetic number, because the mean of its divisors is an integer number (10560060110491).

Almost surely, 2^{21120120220981} is an apocalyptic number.

It is an amenable number.

21120120220981 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120120220981 is an equidigital number, since it uses as much as digits as its factorization.

21120120220981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 31.

The spelling of 21120120220981 in words is "twenty-one trillion, one hundred twenty billion, one hundred twenty million, two hundred twenty thousand, nine hundred eighty-one".