21253230 has 96 divisors (see below), whose sum is σ = 60652800. Its totient is φ = 5139456.

The previous prime is 21253217. The next prime is 21253237. The reversal of 21253230 is 3235212.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253237) 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 47 ways as a sum of consecutive naturals, for example, 44131 + ... + 44609.

It is an arithmetic number, because the mean of its divisors is an integer number (631800).

Almost surely, 2^21253230 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21253230, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30326400).

21253230 is an abundant number, since it is smaller than the sum of its proper divisors (39399570).

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

21253230 is a wasteful number, since it uses less digits than its factorization.

21253230 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 538 (or 535 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 21253230 is about 4610.1225580238. The cubic root of 21253230 is about 276.9969459277.

Adding to 21253230 its reverse (3235212), we get a palindrome (24488442).

The spelling of 21253230 in words is "twenty-one million, two hundred fifty-three thousand, two hundred thirty".