21408960 has 112 divisors (see below), whose sum is σ = 70408800. Its totient is φ = 5505024.

The previous prime is 21408949. The next prime is 21408971. The reversal of 21408960 is 6980412.

It is an interprime number because it is at equal distance from previous prime (21408949) and next prime (21408971).

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 27456 + ... + 28224.

It is an arithmetic number, because the mean of its divisors is an integer number (628650).

Almost surely, 2^21408960 is an apocalyptic number.

21408960 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 21408960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35204400).

21408960 is an abundant number, since it is smaller than the sum of its proper divisors (48999840).

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

21408960 is a wasteful number, since it uses less digits than its factorization.

21408960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 818 (or 808 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 21408960 is about 4626.9817375909. The cubic root of 21408960 is about 277.6718519973.

The spelling of 21408960 in words is "twenty-one million, four hundred eight thousand, nine hundred sixty".