28972217 has 4 divisors (see below), whose sum is σ = 29124096. Its totient is φ = 28820340.

The previous prime is 28972193. The next prime is 28972231. The reversal of 28972217 is 71227982.

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.

It is a cyclic number.

It is not a de Polignac number, because 28972217 - 2¹⁰ = 28971193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28972417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75653 + ... + 76034.

It is an arithmetic number, because the mean of its divisors is an integer number (7281024).

Almost surely, 2^28972217 is an apocalyptic number.

It is an amenable number.

28972217 is a deficient number, since it is larger than the sum of its proper divisors (151879).

28972217 is a wasteful number, since it uses less digits than its factorization.

28972217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151878.

The product of its digits is 28224, while the sum is 38.

The square root of 28972217 is about 5382.5846022148. The cubic root of 28972217 is about 307.1335383714.

The spelling of 28972217 in words is "twenty-eight million, nine hundred seventy-two thousand, two hundred seventeen".