12201991 has 2 divisors, whose sum is σ = 12201992. Its totient is φ = 12201990.

The previous prime is 12201961. The next prime is 12202007. The reversal of 12201991 is 19910221.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 12201991 - 2⁹ = 12201479 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12201901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6100995 + 6100996.

It is an arithmetic number, because the mean of its divisors is an integer number (6100996).

Almost surely, 2^12201991 is an apocalyptic number.

12201991 is a deficient number, since it is larger than the sum of its proper divisors (1).

12201991 is an equidigital number, since it uses as much as digits as its factorization.

12201991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 25.

The square root of 12201991 is about 3493.1348385082. The cubic root of 12201991 is about 230.2202741652.

The spelling of 12201991 in words is "twelve million, two hundred one thousand, nine hundred ninety-one".