28121171 has 4 divisors (see below), whose sum is σ = 30284352. Its totient is φ = 25957992.

The previous prime is 28121161. The next prime is 28121189. The reversal of 28121171 is 17112182.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 17112182 = 2 ⋅8556091.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28121171 is a prime.

It is a super-2 number, since 2×28121171² = 1581600516822482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28121101) 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, 1081571 + ... + 1081596.

It is an arithmetic number, because the mean of its divisors is an integer number (7571088).

Almost surely, 2^28121171 is an apocalyptic number.

28121171 is a deficient number, since it is larger than the sum of its proper divisors (2163181).

28121171 is a wasteful number, since it uses less digits than its factorization.

28121171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2163180.

The product of its digits is 224, while the sum is 23.

The square root of 28121171 is about 5302.9398450294. The cubic root of 28121171 is about 304.0962984107.

The spelling of 28121171 in words is "twenty-eight million, one hundred twenty-one thousand, one hundred seventy-one".