13815921 has 16 divisors (see below), whose sum is σ = 21131264. Its totient is φ = 7865424.

The previous prime is 13815913. The next prime is 13815937. The reversal of 13815921 is 12951831.

It is not a de Polignac number, because 13815921 - 2³ = 13815913 is a prime.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (13815421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5376 + ... + 7518.

It is an arithmetic number, because the mean of its divisors is an integer number (1320704).

Almost surely, 2^13815921 is an apocalyptic number.

It is an amenable number.

13815921 is a deficient number, since it is larger than the sum of its proper divisors (7315343).

13815921 is a wasteful number, since it uses less digits than its factorization.

13815921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2460.

The product of its digits is 2160, while the sum is 30.

The square root of 13815921 is about 3716.9774010612. The cubic root of 13815921 is about 239.9532374170.

The spelling of 13815921 in words is "thirteen million, eight hundred fifteen thousand, nine hundred twenty-one".