21540547 has 24 divisors (see below), whose sum is σ = 27948240. Its totient is φ = 16450560.

The previous prime is 21540529. The next prime is 21540551. The reversal of 21540547 is 74504512.

It is not a de Polignac number, because 21540547 - 2¹¹ = 21538499 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21540587) 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, 15147 + ... + 16507.

It is an arithmetic number, because the mean of its divisors is an integer number (1164510).

Almost surely, 2^21540547 is an apocalyptic number.

21540547 is a deficient number, since it is larger than the sum of its proper divisors (6407693).

21540547 is a wasteful number, since it uses less digits than its factorization.

21540547 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1411 (or 1404 counting only the distinct ones).

The product of its (nonzero) digits is 5600, while the sum is 28.

The square root of 21540547 is about 4641.1794837089. The cubic root of 21540547 is about 278.2395800589.

The spelling of 21540547 in words is "twenty-one million, five hundred forty thousand, five hundred forty-seven".