12021871991 has 2 divisors, whose sum is σ = 12021871992. Its totient is φ = 12021871990.

The previous prime is 12021871937. The next prime is 12021871993. The reversal of 12021871991 is 19917812021.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 12021871991 - 2¹⁰ = 12021870967 is a prime.

Together with 12021871993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12021871993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6010935995 + 6010935996.

It is an arithmetic number, because the mean of its divisors is an integer number (6010935996).

Almost surely, 2^12021871991 is an apocalyptic number.

12021871991 is a deficient number, since it is larger than the sum of its proper divisors (1).

12021871991 is an equidigital number, since it uses as much as digits as its factorization.

12021871991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18144, while the sum is 41.

The spelling of 12021871991 in words is "twelve billion, twenty-one million, eight hundred seventy-one thousand, nine hundred ninety-one".