21543522 has 128 divisors (see below), whose sum is σ = 61544448. Its totient is φ = 4838400.

The previous prime is 21543503. The next prime is 21543527. The reversal of 21543522 is 22534512.

It is a junction number, because it is equal to n+sod(n) for n = 21543492 and 21543501.

It is not an unprimeable number, because it can be changed into a prime (21543527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 101997 + ... + 102207.

It is an arithmetic number, because the mean of its divisors is an integer number (480816).

Almost surely, 2^21543522 is an apocalyptic number.

21543522 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is a pronic number, being equal to 4641×4642.

It is a practical number, because each smaller number is the sum of distinct divisors of 21543522, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30772224).

21543522 is an abundant number, since it is smaller than the sum of its proper divisors (40000926).

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

21543522 is a wasteful number, since it uses less digits than its factorization.

21543522 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 264.

The product of its digits is 2400, while the sum is 24.

The square root of 21543522 is about 4641.4999730691. The cubic root of 21543522 is about 278.2523888430.

The spelling of 21543522 in words is "twenty-one million, five hundred forty-three thousand, five hundred twenty-two".