13405921 has 4 divisors (see below), whose sum is σ = 13633200. Its totient is φ = 13178644.

The previous prime is 13405913. The next prime is 13405927. The reversal of 13405921 is 12950431.

13405921 is digitally balanced in base 2 and base 3, because in such bases 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, and also an emirpimes, since its reverse is a distinct semiprime: 12950431 = 13 ⋅996187.

It is a cyclic number.

It is not a de Polignac number, because 13405921 - 2³ = 13405913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13405927) 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, 113551 + ... + 113668.

It is an arithmetic number, because the mean of its divisors is an integer number (3408300).

Almost surely, 2^13405921 is an apocalyptic number.

It is an amenable number.

13405921 is a deficient number, since it is larger than the sum of its proper divisors (227279).

13405921 is an equidigital number, since it uses as much as digits as its factorization.

13405921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 227278.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 13405921 is about 3661.4097011943. The cubic root of 13405921 is about 237.5557527467. Note that the first 3 decimals are identical.

The spelling of 13405921 in words is "thirteen million, four hundred five thousand, nine hundred twenty-one".