21206541 has 8 divisors (see below), whose sum is σ = 28877184. Its totient is φ = 13836800.

The previous prime is 21206533. The next prime is 21206557. The reversal of 21206541 is 14560212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21206541 - 2³ = 21206533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21206501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75060 + ... + 75341.

It is an arithmetic number, because the mean of its divisors is an integer number (3609648).

Almost surely, 2^21206541 is an apocalyptic number.

It is an amenable number.

21206541 is a deficient number, since it is larger than the sum of its proper divisors (7670643).

21206541 is a wasteful number, since it uses less digits than its factorization.

21206541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150451.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21206541 is about 4605.0560257178. The cubic root of 21206541 is about 276.7939620023.

Adding to 21206541 its reverse (14560212), we get a palindrome (35766753).

The spelling of 21206541 in words is "twenty-one million, two hundred six thousand, five hundred forty-one".