15172121 has 4 divisors (see below), whose sum is σ = 15227172. Its totient is φ = 15117072.

The previous prime is 15172099. The next prime is 15172153. The reversal of 15172121 is 12127151.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12127151 = 157 ⋅77243.

It can be written as a sum of positive squares in 2 ways, for example, as 9388096 + 5784025 = 3064^2 + 2405^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15172121 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 15172093 and 15172102.

It is not an unprimeable number, because it can be changed into a prime (15172181) 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 3 ways as a sum of consecutive naturals, for example, 27110 + ... + 27663.

It is an arithmetic number, because the mean of its divisors is an integer number (3806793).

Almost surely, 2^15172121 is an apocalyptic number.

It is an amenable number.

15172121 is a deficient number, since it is larger than the sum of its proper divisors (55051).

15172121 is an equidigital number, since it uses as much as digits as its factorization.

15172121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55050.

The product of its digits is 140, while the sum is 20.

The square root of 15172121 is about 3895.1406906555. The cubic root of 15172121 is about 247.5609264012.

Adding to 15172121 its reverse (12127151), we get a palindrome (27299272).

The spelling of 15172121 in words is "fifteen million, one hundred seventy-two thousand, one hundred twenty-one".