28191880 has 16 divisors (see below), whose sum is σ = 63431820. Its totient is φ = 11276736.

The previous prime is 28191853. The next prime is 28191893. The reversal of 28191880 is 8819182.

It can be written as a sum of positive squares in 2 ways, for example, as 23020804 + 5171076 = 4798^2 + 2274^2 .

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 3 ways as a sum of consecutive naturals, for example, 352359 + ... + 352438.

Almost surely, 2^28191880 is an apocalyptic number.

28191880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28191880 is an abundant number, since it is smaller than the sum of its proper divisors (35239940).

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

28191880 is a wasteful number, since it uses less digits than its factorization.

28191880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 704808 (or 704804 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 37.

The square root of 28191880 is about 5309.6026216658. The cubic root of 28191880 is about 304.3509623930.

The spelling of 28191880 in words is "twenty-eight million, one hundred ninety-one thousand, eight hundred eighty".