21253288 has 64 divisors (see below), whose sum is σ = 49248000. Its totient is φ = 8397312.

The previous prime is 21253279. The next prime is 21253301. The reversal of 21253288 is 88235212.

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, 37068 + ... + 37636.

It is an arithmetic number, because the mean of its divisors is an integer number (769500).

Almost surely, 2^21253288 is an apocalyptic number.

21253288 is a gapful number since it is divisible by the number (28) 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 21253288, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24624000).

21253288 is an abundant number, since it is smaller than the sum of its proper divisors (27994712).

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

21253288 is a wasteful number, since it uses less digits than its factorization.

21253288 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 634 (or 630 counting only the distinct ones).

The product of its digits is 7680, while the sum is 31.

The square root of 21253288 is about 4610.1288485247. The cubic root of 21253288 is about 276.9971979020.

The spelling of 21253288 in words is "twenty-one million, two hundred fifty-three thousand, two hundred eighty-eight".