28135821 has 16 divisors (see below), whose sum is σ = 42948224. Its totient is φ = 16049664.

The previous prime is 28135781. The next prime is 28135847. The reversal of 28135821 is 12853182.

It is not a de Polignac number, because 28135821 - 2⁹ = 28135309 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28135871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21045 + ... + 22341.

It is an arithmetic number, because the mean of its divisors is an integer number (2684264).

Almost surely, 2^28135821 is an apocalyptic number.

28135821 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28135821 is a deficient number, since it is larger than the sum of its proper divisors (14812403).

28135821 is a wasteful number, since it uses less digits than its factorization.

28135821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2340.

The product of its digits is 3840, while the sum is 30.

The square root of 28135821 is about 5304.3209744509. The cubic root of 28135821 is about 304.1490965602.

The spelling of 28135821 in words is "twenty-eight million, one hundred thirty-five thousand, eight hundred twenty-one".