21408480 has 72 divisors (see below), whose sum is σ = 73061352. Its totient is φ = 5708544.

The previous prime is 21408479. The next prime is 21408493. The reversal of 21408480 is 8480412.

It is a tau number, because it is divible by the number of its divisors (72).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5994 + ... + 8873.

It is an arithmetic number, because the mean of its divisors is an integer number (1014741).

Almost surely, 2^21408480 is an apocalyptic number.

21408480 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21408480 is an abundant number, since it is smaller than the sum of its proper divisors (51652872).

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

21408480 is a wasteful number, since it uses less digits than its factorization.

21408480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14888 (or 14877 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 27.

The square root of 21408480 is about 4626.9298676336. The cubic root of 21408480 is about 277.6697767995.

Adding to 21408480 its reverse (8480412), we get a palindrome (29888892).

The spelling of 21408480 in words is "twenty-one million, four hundred eight thousand, four hundred eighty".