220121201011991 has 2 divisors, whose sum is σ = 220121201011992. Its totient is φ = 220121201011990.

The previous prime is 220121201011967. The next prime is 220121201012039. The reversal of 220121201011991 is 199110102121022.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 220121201011991 - 2¹⁰ = 220121201010967 is a prime.

It is a super-2 number, since 2×220121201011991² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (220121201041991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110060600505995 + 110060600505996.

It is an arithmetic number, because the mean of its divisors is an integer number (110060600505996).

Almost surely, 2^{220121201011991} is an apocalyptic number.

220121201011991 is a deficient number, since it is larger than the sum of its proper divisors (1).

220121201011991 is an equidigital number, since it uses as much as digits as its factorization.

220121201011991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 32.

The spelling of 220121201011991 in words is "two hundred twenty trillion, one hundred twenty-one billion, two hundred one million, eleven thousand, nine hundred ninety-one".