28724219 has 4 divisors (see below), whose sum is σ = 30236040. Its totient is φ = 27212400.

The previous prime is 28724207. The next prime is 28724221. The reversal of 28724219 is 91242782.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28724219 is a prime.

It is a super-2 number, since 2×28724219² = 1650161514319922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28724279) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 755882 + ... + 755919.

It is an arithmetic number, because the mean of its divisors is an integer number (7559010).

Almost surely, 2^28724219 is an apocalyptic number.

28724219 is a deficient number, since it is larger than the sum of its proper divisors (1511821).

28724219 is a wasteful number, since it uses less digits than its factorization.

28724219 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1511820.

The product of its digits is 16128, while the sum is 35.

The square root of 28724219 is about 5359.4980175386. The cubic root of 28724219 is about 306.2546863645.

The spelling of 28724219 in words is "twenty-eight million, seven hundred twenty-four thousand, two hundred nineteen".