21812128 has 24 divisors (see below), whose sum is σ = 46246788. Its totient is φ = 10066944.

The previous prime is 21812113. The next prime is 21812143. The reversal of 21812128 is 82121812.

It is an interprime number because it is at equal distance from previous prime (21812113) and next prime (21812143).

It can be written as a sum of positive squares in 2 ways, for example, as 21790224 + 21904 = 4668^2 + 148^2 .

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

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 3 ways as a sum of consecutive naturals, for example, 25801 + ... + 26632.

Almost surely, 2^21812128 is an apocalyptic number.

It is an amenable number.

21812128 is an abundant number, since it is smaller than the sum of its proper divisors (24434660).

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

21812128 is a wasteful number, since it uses less digits than its factorization.

21812128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52456 (or 52448 counting only the distinct ones).

The product of its digits is 512, while the sum is 25.

The square root of 21812128 is about 4670.3455974906. The cubic root of 21812128 is about 279.4040385580.

The spelling of 21812128 in words is "twenty-one million, eight hundred twelve thousand, one hundred twenty-eight".