21447760 has 40 divisors (see below), whose sum is σ = 50282496. Its totient is φ = 8507520.

The previous prime is 21447749. The next prime is 21447773. The reversal of 21447760 is 6774412.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9105 + ... + 11215.

Almost surely, 2^21447760 is an apocalyptic number.

21447760 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 21447760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25141248).

21447760 is an abundant number, since it is smaller than the sum of its proper divisors (28834736).

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

21447760 is a wasteful number, since it uses less digits than its factorization.

21447760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2251 (or 2245 counting only the distinct ones).

The product of its (nonzero) digits is 9408, while the sum is 31.

The square root of 21447760 is about 4631.1726376804. The cubic root of 21447760 is about 277.8394946719.

It can be divided in two parts, 214 and 47760, that added together give a palindrome (47974).

The spelling of 21447760 in words is "twenty-one million, four hundred forty-seven thousand, seven hundred sixty".