28216909 has 8 divisors (see below), whose sum is σ = 32690240. Its totient is φ = 23854176.

The previous prime is 28216907. The next prime is 28216921. The reversal of 28216909 is 90961282.

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

It is a cyclic number.

It is not a de Polignac number, because 28216909 - 2¹ = 28216907 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28216907) 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, 27099 + ... + 28120.

It is an arithmetic number, because the mean of its divisors is an integer number (4086280).

Almost surely, 2^28216909 is an apocalyptic number.

It is an amenable number.

28216909 is a deficient number, since it is larger than the sum of its proper divisors (4473331).

28216909 is an equidigital number, since it uses as much as digits as its factorization.

28216909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55299.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 28216909 is about 5311.9590548121. The cubic root of 28216909 is about 304.4410042422.

It can be divided in two parts, 2821 and 6909, that added together give a triangular number (9730 = T₁₃₉).

The spelling of 28216909 in words is "twenty-eight million, two hundred sixteen thousand, nine hundred nine".