21284280 has 48 divisors (see below), whose sum is σ = 69175080. Its totient is φ = 5675712.

The previous prime is 21284273. The next prime is 21284281. The reversal of 21284280 is 8248212.

It is a zygodrome in base 3.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21284281) 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 11 ways as a sum of consecutive naturals, for example, 29202 + ... + 29921.

Almost surely, 2^21284280 is an apocalyptic number.

21284280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21284280 is an abundant number, since it is smaller than the sum of its proper divisors (47890800).

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

21284280 is a wasteful number, since it uses less digits than its factorization.

21284280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59140 (or 59133 counting only the distinct ones).

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

The square root of 21284280 is about 4613.4889183784. The cubic root of 21284280 is about 277.1317735928.

The spelling of 21284280 in words is "twenty-one million, two hundred eighty-four thousand, two hundred eighty".