21120321109991 has 2 divisors, whose sum is σ = 21120321109992. Its totient is φ = 21120321109990.

The previous prime is 21120321109969. The next prime is 21120321110047. The reversal of 21120321109991 is 19990112302112.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21120321109991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21120321109691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560160554995 + 10560160554996.

It is an arithmetic number, because the mean of its divisors is an integer number (10560160554996).

Almost surely, 2^{21120321109991} is an apocalyptic number.

21120321109991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120321109991 is an equidigital number, since it uses as much as digits as its factorization.

21120321109991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496, while the sum is 41.

The spelling of 21120321109991 in words is "twenty-one trillion, one hundred twenty billion, three hundred twenty-one million, one hundred nine thousand, nine hundred ninety-one".