21738528 has 144 divisors (see below), whose sum is σ = 72648576. Its totient is φ = 6036480.

The previous prime is 21738503. The next prime is 21738539. The reversal of 21738528 is 82583712.

It is a tau number, because it is divible by the number of its divisors (144).

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 = 21738492 and 21738501.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 82525 + ... + 82787.

It is an arithmetic number, because the mean of its divisors is an integer number (504504).

Almost surely, 2^21738528 is an apocalyptic number.

21738528 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21738528, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36324288).

21738528 is an abundant number, since it is smaller than the sum of its proper divisors (50910048).

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

21738528 is a wasteful number, since it uses less digits than its factorization.

21738528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327 (or 316 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 21738528 is about 4662.4594368209. The cubic root of 21738528 is about 279.0894229102.

It can be divided in two parts, 2173 and 8528, that added together give a palindrome (10701).

The spelling of 21738528 in words is "twenty-one million, seven hundred thirty-eight thousand, five hundred twenty-eight".