13821381 has 48 divisors (see below), whose sum is σ = 24660480. Its totient is φ = 7620480.

The previous prime is 13821377. The next prime is 13821383. The reversal of 13821381 is 18312831.

It is not a de Polignac number, because 13821381 - 2² = 13821377 is a prime.

It is a super-2 number, since 2×13821381² = 382061145494322, which contains 22 as substring.

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 a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13821383) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 40845 + ... + 41181.

It is an arithmetic number, because the mean of its divisors is an integer number (513760).

Almost surely, 2^13821381 is an apocalyptic number.

It is an amenable number.

13821381 is a deficient number, since it is larger than the sum of its proper divisors (10839099).

13821381 is a wasteful number, since it uses less digits than its factorization.

13821381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391 (or 378 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 13821381 is about 3717.7117962532. The cubic root of 13821381 is about 239.9848427928.

The spelling of 13821381 in words is "thirteen million, eight hundred twenty-one thousand, three hundred eighty-one".