21533512 has 64 divisors (see below), whose sum is σ = 54230400. Its totient is φ = 7741440.

The previous prime is 21533507. The next prime is 21533513.

21533512 is nontrivially palindromic in base 10.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is not an unprimeable number, because it can be changed into a prime (21533513) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6664 + ... + 9352.

It is an arithmetic number, because the mean of its divisors is an integer number (847350).

Almost surely, 2^21533512 is an apocalyptic number.

21533512 is a gapful number since it is divisible by the number (22) 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 21533512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27115200).

21533512 is an abundant number, since it is smaller than the sum of its proper divisors (32696888).

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

21533512 is a wasteful number, since it uses less digits than its factorization.

21533512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2726 (or 2722 counting only the distinct ones).

The product of its digits is 900, while the sum is 22.

The square root of 21533512 is about 4640.4215325765. The cubic root of 21533512 is about 278.2092863593.

It can be divided in two parts, 2153 and 3512, that added together give a palindrome (5665).

The spelling of 21533512 in words is "twenty-one million, five hundred thirty-three thousand, five hundred twelve".