21255280 has 40 divisors (see below), whose sum is σ = 50478912. Its totient is φ = 8319744.

The previous prime is 21255277. The next prime is 21255293. The reversal of 21255280 is 8255212.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 934 + ... + 6586.

Almost surely, 2^21255280 is an apocalyptic number.

21255280 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 21255280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25239456).

21255280 is an abundant number, since it is smaller than the sum of its proper divisors (29223632).

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

21255280 is a wasteful number, since it uses less digits than its factorization.

21255280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5713 (or 5707 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 25.

The square root of 21255280 is about 4610.3448894850. The cubic root of 21255280 is about 277.0058516404.

The spelling of 21255280 in words is "twenty-one million, two hundred fifty-five thousand, two hundred eighty".