13681921 has 4 divisors (see below), whose sum is σ = 14925744. Its totient is φ = 12438100.

The previous prime is 13681907. The next prime is 13681951. The reversal of 13681921 is 12918631.

13681921 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 13681921 - 2⁷ = 13681793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13681951) 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, 621895 + ... + 621916.

It is an arithmetic number, because the mean of its divisors is an integer number (3731436).

Almost surely, 2^13681921 is an apocalyptic number.

13681921 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

13681921 is a deficient number, since it is larger than the sum of its proper divisors (1243823).

13681921 is a wasteful number, since it uses less digits than its factorization.

13681921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1243822.

The product of its digits is 2592, while the sum is 31.

The square root of 13681921 is about 3698.9080821237. The cubic root of 13681921 is about 239.1749505373.

The spelling of 13681921 in words is "thirteen million, six hundred eighty-one thousand, nine hundred twenty-one".