28861220 has 24 divisors (see below), whose sum is σ = 60930744. Its totient is φ = 11483136.

The previous prime is 28861219. The next prime is 28861237. The reversal of 28861220 is 2216882.

It can be written as a sum of positive squares in 4 ways, for example, as 6031936 + 22829284 = 2456^2 + 4778^2 .

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 7 ways as a sum of consecutive naturals, for example, 122 + ... + 7598.

It is an arithmetic number, because the mean of its divisors is an integer number (2538781).

Almost surely, 2^28861220 is an apocalyptic number.

28861220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28861220 is an abundant number, since it is smaller than the sum of its proper divisors (32069524).

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

28861220 is a wasteful number, since it uses less digits than its factorization.

28861220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7679 (or 7677 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 29.

The square root of 28861220 is about 5372.2639547960. The cubic root of 28861220 is about 306.7408112047.

The spelling of 28861220 in words is "twenty-eight million, eight hundred sixty-one thousand, two hundred twenty".