13191921 has 12 divisors (see below), whose sum is σ = 19368180. Its totient is φ = 8650080.

The previous prime is 13191917. The next prime is 13191929. The reversal of 13191921 is 12919131.

13191921 is nontrivially palindromic in base 13 and base 14.

13191921 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 7617600 + 5574321 = 2760^2 + 2361^2 .

It is not a de Polignac number, because 13191921 - 2² = 13191917 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (13191929) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11466 + ... + 12563.

It is an arithmetic number, because the mean of its divisors is an integer number (1614015).

Almost surely, 2^13191921 is an apocalyptic number.

It is an amenable number.

13191921 is a deficient number, since it is larger than the sum of its proper divisors (6176259).

13191921 is a wasteful number, since it uses less digits than its factorization.

13191921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24096 (or 24093 counting only the distinct ones).

The product of its digits is 486, while the sum is 27.

The square root of 13191921 is about 3632.0684189591. The cubic root of 13191921 is about 236.2849247100.

It can be divided in two parts, 1319 and 1921, that added together give a triangular number (3240 = T₈₀).

The spelling of 13191921 in words is "thirteen million, one hundred ninety-one thousand, nine hundred twenty-one".