211220010021991 has 2 divisors, whose sum is σ = 211220010021992. Its totient is φ = 211220010021990.

The previous prime is 211220010021929. The next prime is 211220010022009. The reversal of 211220010021991 is 199120010022112.

211220010021991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 211220010021991 - 2¹⁵ = 211220009989223 is a prime.

It is a super-2 number, since 2×211220010021991² (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 (211220010021491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105610005010995 + 105610005010996.

It is an arithmetic number, because the mean of its divisors is an integer number (105610005010996).

Almost surely, 2^{211220010021991} is an apocalyptic number.

211220010021991 is a deficient number, since it is larger than the sum of its proper divisors (1).

211220010021991 is an equidigital number, since it uses as much as digits as its factorization.

211220010021991 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 31.

The spelling of 211220010021991 in words is "two hundred eleven trillion, two hundred twenty billion, ten million, twenty-one thousand, nine hundred ninety-one".