21543030 has 64 divisors (see below), whose sum is σ = 58288320. Its totient is φ = 5660928.

The previous prime is 21543013. The next prime is 21543031. The reversal of 21543030 is 3034512.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21542994 and 21543012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21543031) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19164 + ... + 20256.

It is an arithmetic number, because the mean of its divisors is an integer number (910755).

Almost surely, 2^21543030 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21543030, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29144160).

21543030 is an abundant number, since it is smaller than the sum of its proper divisors (36745290).

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

21543030 is a wasteful number, since it uses less digits than its factorization.

21543030 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1182 (or 1176 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 21543030 is about 4641.4469726584. The cubic root of 21543030 is about 278.2502706313.

Adding to 21543030 its reverse (3034512), we get a palindrome (24577542).

It can be divided in two parts, 2154 and 3030, that added together give a square (5184 = 72²).

The spelling of 21543030 in words is "twenty-one million, five hundred forty-three thousand, thirty".