28191816 has 24 divisors (see below), whose sum is σ = 76353030. Its totient is φ = 9397248.

The previous prime is 28191773. The next prime is 28191829. The reversal of 28191816 is 61819182.

It can be written as a sum of positive squares in only one way, i.e., 20738916 + 7452900 = 4554^2 + 2730^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

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 5 ways as a sum of consecutive naturals, for example, 195705 + ... + 195848.

Almost surely, 2^28191816 is an apocalyptic number.

It is an amenable number.

28191816 is an abundant number, since it is smaller than the sum of its proper divisors (48161214).

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

28191816 is a wasteful number, since it uses less digits than its factorization.

28191816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391565 (or 391558 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 28191816 is about 5309.5965948460. The cubic root of 28191816 is about 304.3507320846.

It can be divided in two parts, 28 and 191816, that added together give a square (191844 = 438²).

The spelling of 28191816 in words is "twenty-eight million, one hundred ninety-one thousand, eight hundred sixteen".