21533536 has 48 divisors (see below), whose sum is σ = 45178560. Its totient is φ = 10074240.

The previous prime is 21533527. The next prime is 21533579. The reversal of 21533536 is 63533512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64891 + ... + 65221.

It is an arithmetic number, because the mean of its divisors is an integer number (941220).

Almost surely, 2^21533536 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 21533536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22589280).

21533536 is an abundant number, since it is smaller than the sum of its proper divisors (23645024).

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

21533536 is a wasteful number, since it uses less digits than its factorization.

21533536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 467 (or 459 counting only the distinct ones).

The product of its digits is 8100, while the sum is 28.

The square root of 21533536 is about 4640.4241185478. The cubic root of 21533536 is about 278.2093897179.

The spelling of 21533536 in words is "twenty-one million, five hundred thirty-three thousand, five hundred thirty-six".