28009920 has 112 divisors (see below), whose sum is σ = 89976960. Its totient is φ = 7382016.

The previous prime is 28009913. The next prime is 28009937. The reversal of 28009920 is 2990082.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 156391 + ... + 156569.

Almost surely, 2^28009920 is an apocalyptic number.

28009920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28009920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44988480).

28009920 is an abundant number, since it is smaller than the sum of its proper divisors (61967040).

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

28009920 is a wasteful number, since it uses less digits than its factorization.

28009920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 362 (or 352 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 28009920 is about 5292.4398910144. The cubic root of 28009920 is about 303.6947536232.

It can be divided in two parts, 2800 and 9920, that added together give a triangular number (12720 = T₁₅₉).

The spelling of 28009920 in words is "twenty-eight million, nine thousand, nine hundred twenty".