21243288 has 64 divisors (see below), whose sum is σ = 58849920. Its totient is φ = 6336000.

The previous prime is 21243263. The next prime is 21243293. The reversal of 21243288 is 88234212.

It is a nude number because it is divisible by every one of its digits.

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, 17088 + ... + 18288.

It is an arithmetic number, because the mean of its divisors is an integer number (919530).

Almost surely, 2^21243288 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21243288, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29424960).

21243288 is an abundant number, since it is smaller than the sum of its proper divisors (37606632).

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

21243288 is a wasteful number, since it uses less digits than its factorization.

21243288 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1288 (or 1284 counting only the distinct ones).

The product of its digits is 6144, while the sum is 30.

The square root of 21243288 is about 4609.0441525331. The cubic root of 21243288 is about 276.9537472678.

The spelling of 21243288 in words is "twenty-one million, two hundred forty-three thousand, two hundred eighty-eight".