21753000 has 96 divisors (see below), whose sum is σ = 73555560. Its totient is φ = 5798400.

The previous prime is 21752999. The next prime is 21753007. The reversal of 21753000 is 35712.

It can be written as a sum of positive squares in 4 ways, for example, as 13003236 + 8749764 = 3606^2 + 2958^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21753007) 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, 7792 + ... + 10208.

It is a vampire number, since it can be written as 3000 ⋅ 7251 (with its own digits).

Almost surely, 2^21753000 is an apocalyptic number.

21753000 is a gapful number since it is divisible by the number (20) 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 21753000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36777780).

21753000 is an abundant number, since it is smaller than the sum of its proper divisors (51802560).

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

21753000 is a wasteful number, since it uses less digits than its factorization.

21753000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2444 (or 2427 counting only the distinct ones).

The product of its (nonzero) digits is 210, while the sum is 18.

The square root of 21753000 is about 4664.0111492148. The cubic root of 21753000 is about 279.1513419473.

Adding to 21753000 its reverse (35712), we get a palindrome (21788712).

The spelling of 21753000 in words is "twenty-one million, seven hundred fifty-three thousand".