28078921 has 8 divisors (see below), whose sum is σ = 30290624. Its totient is φ = 25874640.

The previous prime is 28078907. The next prime is 28078937. The reversal of 28078921 is 12987082.

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 28078921 - 2¹⁹ = 27554633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28078121) 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 7 ways as a sum of consecutive naturals, for example, 7966 + ... + 10936.

It is an arithmetic number, because the mean of its divisors is an integer number (3786328).

Almost surely, 2^28078921 is an apocalyptic number.

It is an amenable number.

28078921 is a deficient number, since it is larger than the sum of its proper divisors (2211703).

28078921 is a wasteful number, since it uses less digits than its factorization.

28078921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3711.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 28078921 is about 5298.9547082420. The cubic root of 28078921 is about 303.9439279374.

The spelling of 28078921 in words is "twenty-eight million, seventy-eight thousand, nine hundred twenty-one".