21045911 has 4 divisors (see below), whose sum is σ = 21232272. Its totient is φ = 20859552.

The previous prime is 21045907. The next prime is 21045917. The reversal of 21045911 is 11954012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21045911 - 2² = 21045907 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 (21045917) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 93011 + ... + 93236.

It is an arithmetic number, because the mean of its divisors is an integer number (5308068).

Almost surely, 2^21045911 is an apocalyptic number.

21045911 is a deficient number, since it is larger than the sum of its proper divisors (186361).

21045911 is a wasteful number, since it uses less digits than its factorization.

21045911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186360.

The product of its (nonzero) digits is 360, while the sum is 23.

The square root of 21045911 is about 4587.5822608429. The cubic root of 21045911 is about 276.0933268020.

Adding to 21045911 its reverse (11954012), we get a palindrome (32999923).

The spelling of 21045911 in words is "twenty-one million, forty-five thousand, nine hundred eleven".