13911721 has 4 divisors (see below), whose sum is σ = 14139844. Its totient is φ = 13683600.

The previous prime is 13911719. The next prime is 13911739. The reversal of 13911721 is 12711931.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12711931 = 19 ⋅669049.

It can be written as a sum of positive squares in 2 ways, for example, as 5588496 + 8323225 = 2364^2 + 2885^2 .

It is a cyclic number.

It is not a de Polignac number, because 13911721 - 2¹ = 13911719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13911791) 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 in 3 ways as a sum of consecutive naturals, for example, 113970 + ... + 114091.

It is an arithmetic number, because the mean of its divisors is an integer number (3534961).

Almost surely, 2^13911721 is an apocalyptic number.

It is an amenable number.

13911721 is a deficient number, since it is larger than the sum of its proper divisors (228123).

13911721 is an equidigital number, since it uses as much as digits as its factorization.

13911721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228122.

The product of its digits is 378, while the sum is 25.

The square root of 13911721 is about 3729.8419537562. The cubic root of 13911721 is about 240.5065746823.

The spelling of 13911721 in words is "thirteen million, nine hundred eleven thousand, seven hundred twenty-one".