13991321 has 4 divisors (see below), whose sum is σ = 14115252. Its totient is φ = 13867392.

The previous prime is 13991309. The next prime is 13991333. The reversal of 13991321 is 12319931.

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

It is an interprime number because it is at equal distance from previous prime (13991309) and next prime (13991333).

It can be written as a sum of positive squares in 2 ways, for example, as 190096 + 13801225 = 436^2 + 3715^2 .

It is a cyclic number.

It is not a de Polignac number, because 13991321 - 2²² = 9797017 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13991371) 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, 61796 + ... + 62021.

It is an arithmetic number, because the mean of its divisors is an integer number (3528813).

Almost surely, 2^13991321 is an apocalyptic number.

It is an amenable number.

13991321 is a deficient number, since it is larger than the sum of its proper divisors (123931).

13991321 is a wasteful number, since it uses less digits than its factorization.

13991321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123930.

The product of its digits is 1458, while the sum is 29.

The square root of 13991321 is about 3740.4974268137. The cubic root of 13991321 is about 240.9644122540.

The spelling of 13991321 in words is "thirteen million, nine hundred ninety-one thousand, three hundred twenty-one".