21204480 has 160 divisors (see below), whose sum is σ = 74245248. Its totient is φ = 5120000.

The previous prime is 21204451. The next prime is 21204487. The reversal of 21204480 is 8440212.

It is a tau number, because it is divible by the number of its divisors (160).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204487) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 84355 + ... + 84605.

Almost surely, 2^21204480 is an apocalyptic number.

21204480 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 21204480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37122624).

21204480 is an abundant number, since it is smaller than the sum of its proper divisors (53040768).

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

21204480 is a wasteful number, since it uses less digits than its factorization.

21204480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 288 (or 272 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 21.

The square root of 21204480 is about 4604.8322445014. The cubic root of 21204480 is about 276.7849947873.

Adding to 21204480 its reverse (8440212), we get a palindrome (29644692).

The spelling of 21204480 in words is "twenty-one million, two hundred four thousand, four hundred eighty".