21238280 has 64 divisors (see below), whose sum is σ = 55226880. Its totient is φ = 7200000.

The previous prime is 21238277. The next prime is 21238303. The reversal of 21238280 is 8283212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27905 + ... + 28655.

It is an arithmetic number, because the mean of its divisors is an integer number (862920).

Almost surely, 2^21238280 is an apocalyptic number.

21238280 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 21238280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27613440).

21238280 is an abundant number, since it is smaller than the sum of its proper divisors (33988600).

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

21238280 is a wasteful number, since it uses less digits than its factorization.

21238280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 870 (or 866 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 21238280 is about 4608.5008408375. The cubic root of 21238280 is about 276.9319820656.

The spelling of 21238280 in words is "twenty-one million, two hundred thirty-eight thousand, two hundred eighty".