13813821 has 28 divisors (see below), whose sum is σ = 23678752. Its totient is φ = 7890696.

The previous prime is 13813801. The next prime is 13813829. The reversal of 13813821 is 12831831.

13813821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 13813821 - 2⁶ = 13813757 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13813829) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 3750 + ... + 6456.

Almost surely, 2^13813821 is an apocalyptic number.

It is an amenable number.

13813821 is a deficient number, since it is larger than the sum of its proper divisors (9864931).

13813821 is an frugal number, since it uses more digits than its factorization.

13813821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2732 (or 2717 counting only the distinct ones).

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

The square root of 13813821 is about 3716.6949027328. The cubic root of 13813821 is about 239.9410792860.

The spelling of 13813821 in words is "thirteen million, eight hundred thirteen thousand, eight hundred twenty-one".