211211020991 has 2 divisors, whose sum is σ = 211211020992. Its totient is φ = 211211020990.

The previous prime is 211211020981. The next prime is 211211021027. The reversal of 211211020991 is 199020112112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 211211020991 - 2¹⁰ = 211211019967 is a prime.

It is a super-2 number, since 2×211211020991² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211211020981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105605510495 + 105605510496.

It is an arithmetic number, because the mean of its divisors is an integer number (105605510496).

Almost surely, 2^211211020991 is an apocalyptic number.

211211020991 is a deficient number, since it is larger than the sum of its proper divisors (1).

211211020991 is an equidigital number, since it uses as much as digits as its factorization.

211211020991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 29.

The spelling of 211211020991 in words is "two hundred eleven billion, two hundred eleven million, twenty thousand, nine hundred ninety-one".