12021991 has 2 divisors, whose sum is σ = 12021992. Its totient is φ = 12021990.

The previous prime is 12021973. The next prime is 12022007. The reversal of 12021991 is 19912021.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 12021991 - 2⁵ = 12021959 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12021491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6010995 + 6010996.

It is an arithmetic number, because the mean of its divisors is an integer number (6010996).

Almost surely, 2^12021991 is an apocalyptic number.

12021991 is a deficient number, since it is larger than the sum of its proper divisors (1).

12021991 is an equidigital number, since it uses as much as digits as its factorization.

12021991 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 25.

The square root of 12021991 is about 3467.2742896979. The cubic root of 12021991 is about 229.0826154500.

The spelling of 12021991 in words is "twelve million, twenty-one thousand, nine hundred ninety-one".