28001800 has 24 divisors (see below), whose sum is σ = 65104650. Its totient is φ = 11200640.

The previous prime is 28001789. The next prime is 28001819. The reversal of 28001800 is 810082.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 20958084 + 7043716 = 4578^2 + 2654^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 69805 + ... + 70204.

Almost surely, 2^28001800 is an apocalyptic number.

28001800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28001800 is an abundant number, since it is smaller than the sum of its proper divisors (37102850).

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

28001800 is a wasteful number, since it uses less digits than its factorization.

28001800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140025 (or 140016 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 28001800 is about 5291.6727034086. The cubic root of 28001800 is about 303.6654040245.

Adding to 28001800 its reverse (810082), we get a palindrome (28811882).

The spelling of 28001800 in words is "twenty-eight million, one thousand, eight hundred".