21543380 has 24 divisors (see below), whose sum is σ = 45668448. Its totient is φ = 8535968.

The previous prime is 21543373. The next prime is 21543407. The reversal of 21543380 is 8334512.

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, 2894 + ... + 7173.

It is an arithmetic number, because the mean of its divisors is an integer number (1902852).

Almost surely, 2^21543380 is an apocalyptic number.

21543380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21543380 is an abundant number, since it is smaller than the sum of its proper divisors (24125068).

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

21543380 is a wasteful number, since it uses less digits than its factorization.

21543380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10183 (or 10181 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 21543380 is about 4641.4846762647. The cubic root of 21543380 is about 278.2517774925.

Adding to 21543380 its reverse (8334512), we get a palindrome (29877892).

The spelling of 21543380 in words is "twenty-one million, five hundred forty-three thousand, three hundred eighty".