21869028 has 72 divisors (see below), whose sum is σ = 58094400. Its totient is φ = 7192800.

The previous prime is 21869027. The next prime is 21869033. The reversal of 21869028 is 82096812.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21868983 and 21869001.

It is not an unprimeable number, because it can be changed into a prime (21869027) 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 23 ways as a sum of consecutive naturals, for example, 144753 + ... + 144903.

Almost surely, 2^21869028 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21869028, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29047200).

21869028 is an abundant number, since it is smaller than the sum of its proper divisors (36225372).

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

21869028 is a wasteful number, since it uses less digits than its factorization.

21869028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319 (or 305 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 21869028 is about 4676.4332562328. The cubic root of 21869028 is about 279.6467824978.

The spelling of 21869028 in words is "twenty-one million, eight hundred sixty-nine thousand, twenty-eight".