21838356 has 48 divisors (see below), whose sum is σ = 56929600. Its totient is φ = 7239456.

The previous prime is 21838351. The next prime is 21838361. The reversal of 21838356 is 65383812.

It is an interprime number because it is at equal distance from previous prime (21838351) and next prime (21838361).

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

It is a self number, because there is not a number n which added to its sum of digits gives 21838356.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21838351) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 24291 + ... + 25173.

Almost surely, 2^21838356 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 21838356, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28464800).

21838356 is an abundant number, since it is smaller than the sum of its proper divisors (35091244).

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

21838356 is a wasteful number, since it uses less digits than its factorization.

21838356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1125 (or 1117 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 21838356 is about 4673.1526831466. The cubic root of 21838356 is about 279.5159835245.

The spelling of 21838356 in words is "twenty-one million, eight hundred thirty-eight thousand, three hundred fifty-six".