28016921 has 8 divisors (see below), whose sum is σ = 29673024. Its totient is φ = 26397360.

The previous prime is 28016897. The next prime is 28016957. The reversal of 28016921 is 12961082.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28016921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28016971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7550 + ... + 10631.

It is an arithmetic number, because the mean of its divisors is an integer number (3709128).

Almost surely, 2^28016921 is an apocalyptic number.

It is an amenable number.

28016921 is a deficient number, since it is larger than the sum of its proper divisors (1656103).

28016921 is a wasteful number, since it uses less digits than its factorization.

28016921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18271.

The product of its (nonzero) digits is 1728, while the sum is 29.

The square root of 28016921 is about 5293.1012648541. The cubic root of 28016921 is about 303.7200540626.

The spelling of 28016921 in words is "twenty-eight million, sixteen thousand, nine hundred twenty-one".