28217215 has 8 divisors (see below), whose sum is σ = 36465408. Its totient is φ = 20837280.

The previous prime is 28217213. The next prime is 28217221. The reversal of 28217215 is 51271282.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 28217215 - 2¹ = 28217213 is a prime.

It is a super-2 number, since 2×28217215² = 1592422444712450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28217213) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 216991 + ... + 217120.

It is an arithmetic number, because the mean of its divisors is an integer number (4558176).

Almost surely, 2^28217215 is an apocalyptic number.

28217215 is a deficient number, since it is larger than the sum of its proper divisors (8248193).

28217215 is a wasteful number, since it uses less digits than its factorization.

28217215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 434129.

The product of its digits is 2240, while the sum is 28.

The square root of 28217215 is about 5311.9878576668. The cubic root of 28217215 is about 304.4421047480.

Adding to 28217215 its reverse (51271282), we get a palindrome (79488497).

The spelling of 28217215 in words is "twenty-eight million, two hundred seventeen thousand, two hundred fifteen".