28821520 has 160 divisors (see below), whose sum is σ = 85494528. Its totient is φ = 8792064.

The previous prime is 28821503. The next prime is 28821539. The reversal of 28821520 is 2512882.

It is a super-2 number, since 2×28821520² = 1661360030220800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 269307 + ... + 269413.

Almost surely, 2^28821520 is an apocalyptic number.

28821520 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 28821520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42747264).

28821520 is an abundant number, since it is smaller than the sum of its proper divisors (56673008).

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

28821520 is a wasteful number, since it uses less digits than its factorization.

28821520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177 (or 171 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 28.

The square root of 28821520 is about 5368.5677792126. The cubic root of 28821520 is about 306.6001010742.

The spelling of 28821520 in words is "twenty-eight million, eight hundred twenty-one thousand, five hundred twenty".