1323211991 has 2 divisors, whose sum is σ = 1323211992. Its totient is φ = 1323211990.

The previous prime is 1323211987. The next prime is 1323212069. The reversal of 1323211991 is 1991123231.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1323211991 - 2² = 1323211987 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1323211921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 661605995 + 661605996.

It is an arithmetic number, because the mean of its divisors is an integer number (661605996).

Almost surely, 2^1323211991 is an apocalyptic number.

1323211991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1323211991 is an equidigital number, since it uses as much as digits as its factorization.

1323211991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2916, while the sum is 32.

The square root of 1323211991 is about 36375.9809627177. The cubic root of 1323211991 is about 1097.8503447867.

It can be divided in two parts, 132 and 3211991, that added together give a palindrome (3212123).

The spelling of 1323211991 in words is "one billion, three hundred twenty-three million, two hundred eleven thousand, nine hundred ninety-one".