13921891 has 2 divisors, whose sum is σ = 13921892. Its totient is φ = 13921890.

The previous prime is 13921871. The next prime is 13921907. The reversal of 13921891 is 19812931.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13921891 is a prime.

It is not a weakly prime, because it can be changed into another prime (13921801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6960945 + 6960946.

It is an arithmetic number, because the mean of its divisors is an integer number (6960946).

Almost surely, 2^13921891 is an apocalyptic number.

13921891 is a deficient number, since it is larger than the sum of its proper divisors (1).

13921891 is an equidigital number, since it uses as much as digits as its factorization.

13921891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 34.

The square root of 13921891 is about 3731.2050332299. The cubic root of 13921891 is about 240.5651669078.

The spelling of 13921891 in words is "thirteen million, nine hundred twenty-one thousand, eight hundred ninety-one".