21109248 has 100 divisors (see below), whose sum is σ = 63129330. Its totient is φ = 7022592.

The previous prime is 21109243. The next prime is 21109261. The reversal of 21109248 is 84290112.

It can be written as a sum of positive squares in only one way, i.e., 15116544 + 5992704 = 3888^2 + 2448^2 .

It is a super-2 number, since 2×21109248² = 891200702251008, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21109241) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 41218 + ... + 41726.

Almost surely, 2^21109248 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 21109248, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31564665).

21109248 is an abundant number, since it is smaller than the sum of its proper divisors (42020082).

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

21109248 is an frugal number, since it uses more digits than its factorization.

21109248 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 539 (or 514 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 21109248 is about 4594.4801664606. The cubic root of 21109248 is about 276.3700141229.

The spelling of 21109248 in words is "twenty-one million, one hundred nine thousand, two hundred forty-eight".