21478320 has 120 divisors (see below), whose sum is σ = 75325536. Its totient is φ = 5474304.

The previous prime is 21478313. The next prime is 21478333. The reversal of 21478320 is 2387412.

It is a tau number, because it is divible by the number of its divisors (120).

It is a super-2 number, since 2×21478320² = 922636460044800, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15912 + ... + 17208.

Almost surely, 2^21478320 is an apocalyptic number.

21478320 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 21478320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37662768).

21478320 is an abundant number, since it is smaller than the sum of its proper divisors (53847216).

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

21478320 is a wasteful number, since it uses less digits than its factorization.

21478320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1339 (or 1330 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 21478320 is about 4634.4708435807. The cubic root of 21478320 is about 277.9713926017.

The spelling of 21478320 in words is "twenty-one million, four hundred seventy-eight thousand, three hundred twenty".