21753536 has 56 divisors (see below), whose sum is σ = 50231040. Its totient is φ = 9153792.

The previous prime is 21753533. The next prime is 21753547. The reversal of 21753536 is 63535712.

It is a tau number, because it is divible by the number of its divisors (56).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is not an unprimeable number, because it can be changed into a prime (21753533) 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 7 ways as a sum of consecutive naturals, for example, 26021 + ... + 26843.

Almost surely, 2^21753536 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 21753536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25115520).

21753536 is an abundant number, since it is smaller than the sum of its proper divisors (28477504).

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

21753536 is an equidigital number, since it uses as much as digits as its factorization.

21753536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 901 (or 891 counting only the distinct ones).

The product of its digits is 18900, while the sum is 32.

The square root of 21753536 is about 4664.0686101300. The cubic root of 21753536 is about 279.1536347175.

The spelling of 21753536 in words is "twenty-one million, seven hundred fifty-three thousand, five hundred thirty-six".