28123812 has 18 divisors (see below), whose sum is σ = 71090838. Its totient is φ = 9374592.

The previous prime is 28123807. The next prime is 28123859. The reversal of 28123812 is 21832182.

28123812 is a `hidden beast` number, since 281 + 2 + 381 + 2 = 666.

It can be written as a sum of positive squares in only one way, i.e., 23561316 + 4562496 = 4854^2 + 2136^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×28123812² = 1581897602822688, which contains 22 as substring.

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, 390573 + ... + 390644.

It is an arithmetic number, because the mean of its divisors is an integer number (3949491).

Almost surely, 2^28123812 is an apocalyptic number.

It is an amenable number.

28123812 is an abundant number, since it is smaller than the sum of its proper divisors (42967026).

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

28123812 is a wasteful number, since it uses less digits than its factorization.

28123812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 781227 (or 781222 counting only the distinct ones).

The product of its digits is 1536, while the sum is 27.

The square root of 28123812 is about 5303.1888520022. The cubic root of 28123812 is about 304.1058178482.

Adding to 28123812 its reverse (21832182), we get a palindrome (49955994).

The spelling of 28123812 in words is "twenty-eight million, one hundred twenty-three thousand, eight hundred twelve".