21530600 has 144 divisors (see below), whose sum is σ = 63081900. Its totient is φ = 6814080.

The previous prime is 21530569. The next prime is 21530609. The reversal of 21530600 is 603512.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 6 ways, for example, as 2328676 + 19201924 = 1526^2 + 4382^2 .

It is not an unprimeable number, because it can be changed into a prime (21530609) 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 35 ways as a sum of consecutive naturals, for example, 1656194 + ... + 1656206.

Almost surely, 2^21530600 is an apocalyptic number.

21530600 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 21530600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31540950).

21530600 is an abundant number, since it is smaller than the sum of its proper divisors (41551300).

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

21530600 is a wasteful number, since it uses less digits than its factorization.

21530600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69 (or 27 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 21530600 is about 4640.1077573694. The cubic root of 21530600 is about 278.1967449469.

The spelling of 21530600 in words is "twenty-one million, five hundred thirty thousand, six hundred".