21441680 has 80 divisors (see below), whose sum is σ = 54840240. Its totient is φ = 7747584.

The previous prime is 21441661. The next prime is 21441689. The reversal of 21441680 is 8614412.

It can be written as a sum of positive squares in 8 ways, for example, as 1763584 + 19678096 = 1328^2 + 4436^2 .

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 (26).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21441689) 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, 54926 + ... + 55314.

It is an arithmetic number, because the mean of its divisors is an integer number (685503).

Almost surely, 2^21441680 is an apocalyptic number.

21441680 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 21441680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27420120).

21441680 is an abundant number, since it is smaller than the sum of its proper divisors (33398560).

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

21441680 is a wasteful number, since it uses less digits than its factorization.

21441680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 468 (or 462 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 21441680 is about 4630.5161699318. The cubic root of 21441680 is about 277.8132382582.

The spelling of 21441680 in words is "twenty-one million, four hundred forty-one thousand, six hundred eighty".