21089838 has 64 divisors (see below), whose sum is σ = 53084160. Its totient is φ = 5426400.

The previous prime is 21089833. The next prime is 21089839. The reversal of 21089838 is 83898012.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 21089796 and 21089805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21089833) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 88123 + ... + 88361.

It is an arithmetic number, because the mean of its divisors is an integer number (829440).

Almost surely, 2^21089838 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21089838, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26542080).

21089838 is an abundant number, since it is smaller than the sum of its proper divisors (31994322).

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

21089838 is a wasteful number, since it uses less digits than its factorization.

21089838 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 453.

The product of its (nonzero) digits is 27648, while the sum is 39.

The square root of 21089838 is about 4592.3673633541. The cubic root of 21089838 is about 276.2852805346.

The spelling of 21089838 in words is "twenty-one million, eighty-nine thousand, eight hundred thirty-eight".