15328221 has 4 divisors (see below), whose sum is σ = 20437632. Its totient is φ = 10218812.

The previous prime is 15328217. The next prime is 15328241. The reversal of 15328221 is 12282351.

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: 12282351 = 3 ⋅4094117.

It is a cyclic number.

It is not a de Polignac number, because 15328221 - 2² = 15328217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 15328191 and 15328200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15328241) 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, 2554701 + ... + 2554706.

It is an arithmetic number, because the mean of its divisors is an integer number (5109408).

Almost surely, 2^15328221 is an apocalyptic number.

It is an amenable number.

15328221 is a deficient number, since it is larger than the sum of its proper divisors (5109411).

15328221 is an equidigital number, since it uses as much as digits as its factorization.

15328221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5109410.

The product of its digits is 960, while the sum is 24.

The square root of 15328221 is about 3915.1272009987. The cubic root of 15328221 is about 248.4070502691.

The spelling of 15328221 in words is "fifteen million, three hundred twenty-eight thousand, two hundred twenty-one".