13538721 has 8 divisors (see below), whose sum is σ = 20630464. Its totient is φ = 7736400.

The previous prime is 13538687. The next prime is 13538729. The reversal of 13538721 is 12783531.

13538721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 13538721 - 2¹⁰ = 13537697 is a prime.

It is the 3680-th Hogben number.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (13538729) by changing a digit.

It is a nontrivial repunit in base 3679.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 322330 + ... + 322371.

It is an arithmetic number, because the mean of its divisors is an integer number (2578808).

Almost surely, 2^13538721 is an apocalyptic number.

It is an amenable number.

13538721 is a deficient number, since it is larger than the sum of its proper divisors (7091743).

13538721 is an equidigital number, since it uses as much as digits as its factorization.

13538721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644711.

The product of its digits is 5040, while the sum is 30.

The square root of 13538721 is about 3679.5001019160. The cubic root of 13538721 is about 238.3375914389.

The spelling of 13538721 in words is "thirteen million, five hundred thirty-eight thousand, seven hundred twenty-one".