12538721 has 4 divisors (see below), whose sum is σ = 13503252. Its totient is φ = 11574192.

The previous prime is 12538679. The next prime is 12538723. The reversal of 12538721 is 12783521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12783521 = 349 ⋅36629.

It can be written as a sum of positive squares in 2 ways, for example, as 3150625 + 9388096 = 1775^2 + 3064^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12538721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (12538723) 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, 482246 + ... + 482271.

It is an arithmetic number, because the mean of its divisors is an integer number (3375813).

Almost surely, 2^12538721 is an apocalyptic number.

It is an amenable number.

12538721 is a deficient number, since it is larger than the sum of its proper divisors (964531).

12538721 is an equidigital number, since it uses as much as digits as its factorization.

12538721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 964530.

The product of its digits is 3360, while the sum is 29.

The square root of 12538721 is about 3541.0056481175. The cubic root of 12538721 is about 232.3188306154.

The spelling of 12538721 in words is "twelve million, five hundred thirty-eight thousand, seven hundred twenty-one".