1323201991 has 2 divisors, whose sum is σ = 1323201992. Its totient is φ = 1323201990.

The previous prime is 1323201989. The next prime is 1323202039. The reversal of 1323201991 is 1991023231.

It is a weak prime.

It is an emirp because it is prime and its reverse (1991023231) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1323201991 - 2¹ = 1323201989 is a prime.

Together with 1323201989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1323201931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 661600995 + 661600996.

It is an arithmetic number, because the mean of its divisors is an integer number (661600996).

Almost surely, 2^1323201991 is an apocalyptic number.

1323201991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1323201991 is an equidigital number, since it uses as much as digits as its factorization.

1323201991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 1323201991 is about 36375.8435091202. The cubic root of 1323201991 is about 1097.8475791600.

The spelling of 1323201991 in words is "one billion, three hundred twenty-three million, two hundred one thousand, nine hundred ninety-one".