28100000 has 72 divisors (see below), whose sum is σ = 69393996. Its totient is φ = 11200000.

The previous prime is 28099999. The next prime is 28100011. The reversal of 28100000 is 182.

It can be written as a sum of positive squares in 6 ways, for example, as 1926544 + 26173456 = 1388^2 + 5116^2 .

It is a super-2 number, since 2×28100000² = 1579220000000000, which contains 22 as substring.

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 11 ways as a sum of consecutive naturals, for example, 99860 + ... + 100140.

Almost surely, 2^28100000 is an apocalyptic number.

28100000 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 28100000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34696998).

28100000 is an abundant number, since it is smaller than the sum of its proper divisors (41293996).

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

28100000 is an frugal number, since it uses more digits than its factorization.

28100000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 316 (or 288 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 28100000 is about 5300.9433122794. The cubic root of 28100000 is about 304.0199663710.

Adding to 28100000 its reverse (182), we get a palindrome (28100182).

The spelling of 28100000 in words is "twenty-eight million, one hundred thousand".