28021680 has 80 divisors (see below), whose sum is σ = 96526560. Its totient is φ = 7471872.

The previous prime is 28021673. The next prime is 28021703. The reversal of 28021680 is 8612082.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 4327 + ... + 8646.

It is an arithmetic number, because the mean of its divisors is an integer number (1206582).

Almost surely, 2^28021680 is an apocalyptic number.

28021680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28021680 is an abundant number, since it is smaller than the sum of its proper divisors (68504880).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28021680 is a wasteful number, since it uses less digits than its factorization.

28021680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12995 (or 12983 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 28021680 is about 5293.5507931822. The cubic root of 28021680 is about 303.7372498840.

The spelling of 28021680 in words is "twenty-eight million, twenty-one thousand, six hundred eighty".