13209991 has 2 divisors, whose sum is σ = 13209992. Its totient is φ = 13209990.

The previous prime is 13209983. The next prime is 13210013. The reversal of 13209991 is 19990231.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 13209991 - 2³ = 13209983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13209191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6604995 + 6604996.

It is an arithmetic number, because the mean of its divisors is an integer number (6604996).

Almost surely, 2^13209991 is an apocalyptic number.

13209991 is a deficient number, since it is larger than the sum of its proper divisors (1).

13209991 is an equidigital number, since it uses as much as digits as its factorization.

13209991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 13209991 is about 3634.5551309617. Note that the first 3 decimals coincide. The cubic root of 13209991 is about 236.3927614325.

It can be divided in two parts, 1320 and 9991, that added together give a palindrome (11311).

The spelling of 13209991 in words is "thirteen million, two hundred nine thousand, nine hundred ninety-one".