21304500 has 96 divisors (see below), whose sum is σ = 70936320. Its totient is φ = 4867200.

The previous prime is 21304499. The next prime is 21304501. The reversal of 21304500 is 540312.

It is an interprime number because it is at equal distance from previous prime (21304499) and next prime (21304501).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21304500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21304501) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9486 + ... + 11514.

It is an arithmetic number, because the mean of its divisors is an integer number (738920).

Almost surely, 2^21304500 is an apocalyptic number.

21304500 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 21304500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35468160).

21304500 is an abundant number, since it is smaller than the sum of its proper divisors (49631820).

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

21304500 is a wasteful number, since it uses less digits than its factorization.

21304500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2058 (or 2046 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 15.

The square root of 21304500 is about 4615.6797982529. The cubic root of 21304500 is about 277.2195039260.

Adding to 21304500 its reverse (540312), we get a palindrome (21844812).

The spelling of 21304500 in words is "twenty-one million, three hundred four thousand, five hundred".