21536541 has 12 divisors (see below), whose sum is σ = 33501468. Its totient is φ = 13253184.

The previous prime is 21536539. The next prime is 21536549. The reversal of 21536541 is 14563512.

21536541 is a `hidden beast` number, since 2 + 1 + 5 + 3 + 654 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 4347225 + 17189316 = 2085^2 + 4146^2 .

It is not a de Polignac number, because 21536541 - 2¹ = 21536539 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21536549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 91920 + ... + 92153.

It is an arithmetic number, because the mean of its divisors is an integer number (2791789).

Almost surely, 2^21536541 is an apocalyptic number.

It is an amenable number.

21536541 is a deficient number, since it is larger than the sum of its proper divisors (11964927).

21536541 is a wasteful number, since it uses less digits than its factorization.

21536541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184092 (or 184089 counting only the distinct ones).

The product of its digits is 3600, while the sum is 27.

The square root of 21536541 is about 4640.7478923122. The cubic root of 21536541 is about 278.2223304681. Note that the first 3 decimals are identical.

The spelling of 21536541 in words is "twenty-one million, five hundred thirty-six thousand, five hundred forty-one".