21241680 has 80 divisors (see below), whose sum is σ = 66882624. Its totient is φ = 5575680.

The previous prime is 21241667. The next prime is 21241723. The reversal of 21241680 is 8614212.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21241680.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15420 + ... + 16740.

Almost surely, 2^21241680 is an apocalyptic number.

21241680 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 21241680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33441312).

21241680 is an abundant number, since it is smaller than the sum of its proper divisors (45640944).

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

21241680 is a wasteful number, since it uses less digits than its factorization.

21241680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1404 (or 1398 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 21241680 is about 4608.8697095926. The cubic root of 21241680 is about 276.9467591333.

Adding to 21241680 its reverse (8614212), we get a palindrome (29855892).

The spelling of 21241680 in words is "twenty-one million, two hundred forty-one thousand, six hundred eighty".