21111541 has 4 divisors (see below), whose sum is σ = 23030784. Its totient is φ = 19192300.

The previous prime is 21111533. The next prime is 21111611. The reversal of 21111541 is 14511112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21111541 - 2³ = 21111533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111521) 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 3 ways as a sum of consecutive naturals, for example, 959605 + ... + 959626.

It is an arithmetic number, because the mean of its divisors is an integer number (5757696).

Almost surely, 2^21111541 is an apocalyptic number.

It is an amenable number.

21111541 is a deficient number, since it is larger than the sum of its proper divisors (1919243).

21111541 is a wasteful number, since it uses less digits than its factorization.

21111541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1919242.

The product of its digits is 40, while the sum is 16.

The square root of 21111541 is about 4594.7296982521. The cubic root of 21111541 is about 276.3800206929.

Adding to 21111541 its reverse (14511112), we get a palindrome (35622653).

The spelling of 21111541 in words is "twenty-one million, one hundred eleven thousand, five hundred forty-one".