13131821 has 4 divisors (see below), whose sum is σ = 13158432. Its totient is φ = 13105212.

The previous prime is 13131791. The next prime is 13131851. The reversal of 13131821 is 12813131.

13131821 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 an interprime number because it is at equal distance from previous prime (13131791) and next prime (13131851).

It is a cyclic number.

It is not a de Polignac number, because 13131821 - 2¹⁴ = 13115437 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 13131793 and 13131802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13131851) 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, 12551 + ... + 13556.

It is an arithmetic number, because the mean of its divisors is an integer number (3289608).

Almost surely, 2^13131821 is an apocalyptic number.

It is an amenable number.

13131821 is a deficient number, since it is larger than the sum of its proper divisors (26611).

13131821 is an equidigital number, since it uses as much as digits as its factorization.

13131821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26610.

The product of its digits is 144, while the sum is 20.

The square root of 13131821 is about 3623.7854517065. The cubic root of 13131821 is about 235.9255546574.

Adding to 13131821 its reverse (12813131), we get a palindrome (25944952).

The spelling of 13131821 in words is "thirteen million, one hundred thirty-one thousand, eight hundred twenty-one".