13820991 has 4 divisors (see below), whose sum is σ = 18427992. Its totient is φ = 9213992.

The previous prime is 13820981. The next prime is 13821007. The reversal of 13820991 is 19902831.

13820991 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 13820991 - 2⁵ = 13820959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13820981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2303496 + ... + 2303501.

It is an arithmetic number, because the mean of its divisors is an integer number (4606998).

Almost surely, 2^13820991 is an apocalyptic number.

13820991 is a deficient number, since it is larger than the sum of its proper divisors (4607001).

13820991 is an equidigital number, since it uses as much as digits as its factorization.

13820991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4607000.

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 13820991 is about 3717.6593442649. The cubic root of 13820991 is about 239.9825855420.

The spelling of 13820991 in words is "thirteen million, eight hundred twenty thousand, nine hundred ninety-one".