20012110991 has 2 divisors, whose sum is σ = 20012110992. Its totient is φ = 20012110990.

The previous prime is 20012110961. The next prime is 20012111023. The reversal of 20012110991 is 19901121002.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20012110991 - 2¹⁰ = 20012109967 is a prime.

It is a super-2 number, since 2×20012110991² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20012110991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20012110961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10006055495 + 10006055496.

It is an arithmetic number, because the mean of its divisors is an integer number (10006055496).

Almost surely, 2^20012110991 is an apocalyptic number.

20012110991 is a deficient number, since it is larger than the sum of its proper divisors (1).

20012110991 is an equidigital number, since it uses as much as digits as its factorization.

20012110991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 26.

Adding to 20012110991 its reverse (19901121002), we get a palindrome (39913231993).

It can be divided in two parts, 200121 and 10991, that added together give a palindrome (211112).

The spelling of 20012110991 in words is "twenty billion, twelve million, one hundred ten thousand, nine hundred ninety-one".