21579543 has 24 divisors (see below), whose sum is σ = 33078240. Its totient is φ = 13527360.

The previous prime is 21579517. The next prime is 21579557. The reversal of 21579543 is 34597512.

It is not a de Polignac number, because 21579543 - 2⁶ = 21579479 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21579498 and 21579507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21579043) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11773 + ... + 13481.

It is an arithmetic number, because the mean of its divisors is an integer number (1378260).

Almost surely, 2^21579543 is an apocalyptic number.

21579543 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21579543 is a deficient number, since it is larger than the sum of its proper divisors (11498697).

21579543 is a wasteful number, since it uses less digits than its factorization.

21579543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1799 (or 1796 counting only the distinct ones).

The product of its digits is 37800, while the sum is 36.

The square root of 21579543 is about 4645.3786713249. The cubic root of 21579543 is about 278.4073828180.

It can be divided in two parts, 21579 and 543, that added together give a palindrome (22122).

The spelling of 21579543 in words is "twenty-one million, five hundred seventy-nine thousand, five hundred forty-three".