21455280 has 400 divisors, whose sum is σ = 95065344. Its totient is φ = 4354560.

The previous prime is 21455279. The next prime is 21455281. The reversal of 21455280 is 8255412.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21455279) and next prime (21455281).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nialpdrome in base 9.

It is a zygodrome in base 9.

It is not an unprimeable number, because it can be changed into a prime (21455281) by changing a digit.

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 79 ways as a sum of consecutive naturals, for example, 498939 + ... + 498981.

It is a vampire number, since it can be written as 2520 ⋅ 8514 (with its own digits).

Almost surely, 2^21455280 is an apocalyptic number.

21455280 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 21455280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47532672).

21455280 is an abundant number, since it is smaller than the sum of its proper divisors (73610064).

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

21455280 is a wasteful number, since it uses less digits than its factorization.

21455280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86 (or 71 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 27.

The square root of 21455280 is about 4631.9844559325. The cubic root of 21455280 is about 277.8719628466.

The spelling of 21455280 in words is "twenty-one million, four hundred fifty-five thousand, two hundred eighty".