21556480 has 72 divisors (see below), whose sum is σ = 56365344. Its totient is φ = 7833600.

The previous prime is 21556477. The next prime is 21556481. The reversal of 21556480 is 8465512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21556481) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13315 + ... + 14845.

It is an arithmetic number, because the mean of its divisors is an integer number (782852).

Almost surely, 2^21556480 is an apocalyptic number.

21556480 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 21556480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28182672).

21556480 is an abundant number, since it is smaller than the sum of its proper divisors (34808864).

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

21556480 is a wasteful number, since it uses less digits than its factorization.

21556480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1563 (or 1549 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 31.

The square root of 21556480 is about 4642.8956481920. The cubic root of 21556480 is about 278.3081654208.

The spelling of 21556480 in words is "twenty-one million, five hundred fifty-six thousand, four hundred eighty".