13821231 has 4 divisors (see below), whose sum is σ = 18428312. Its totient is φ = 9214152.

The previous prime is 13821217. The next prime is 13821233. The reversal of 13821231 is 13212831.

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

It is not a de Polignac number, because 13821231 - 2⁶ = 13821167 is a prime.

It is a super-2 number, since 2×13821231² = 382052852710722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 13821198 and 13821207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13821233) 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, 2303536 + ... + 2303541.

It is an arithmetic number, because the mean of its divisors is an integer number (4607078).

Almost surely, 2^13821231 is an apocalyptic number.

13821231 is a deficient number, since it is larger than the sum of its proper divisors (4607081).

13821231 is an equidigital number, since it uses as much as digits as its factorization.

13821231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4607080.

The product of its digits is 288, while the sum is 21.

The square root of 13821231 is about 3717.6916224991. The cubic root of 13821231 is about 239.9839746244.

Subtracting from 13821231 its reverse (13212831), we obtain a square (608400 = 780²).

The spelling of 13821231 in words is "thirteen million, eight hundred twenty-one thousand, two hundred thirty-one".