21109284 has 72 divisors (see below), whose sum is σ = 61425728. Its totient is φ = 5987520.

The previous prime is 21109273. The next prime is 21109313. The reversal of 21109284 is 48290112.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 52974 + ... + 53370.

Almost surely, 2^21109284 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 21109284, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30712864).

21109284 is an abundant number, since it is smaller than the sum of its proper divisors (40316444).

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

21109284 is a wasteful number, since it uses less digits than its factorization.

21109284 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 625 (or 620 counting only the distinct ones).

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

The square root of 21109284 is about 4594.4840842036. The cubic root of 21109284 is about 276.3701712313.

Adding to 21109284 its reverse (48290112), we get a palindrome (69399396).

The spelling of 21109284 in words is "twenty-one million, one hundred nine thousand, two hundred eighty-four".