21240911 has 8 divisors (see below), whose sum is σ = 21836304. Its totient is φ = 20649280.

The previous prime is 21240907. The next prime is 21240913. The reversal of 21240911 is 11904212.

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

It is a cyclic number.

It is not a de Polignac number, because 21240911 - 2² = 21240907 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 (21240913) 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, 13481 + ... + 14973.

It is an arithmetic number, because the mean of its divisors is an integer number (2729538).

Almost surely, 2^21240911 is an apocalyptic number.

21240911 is a deficient number, since it is larger than the sum of its proper divisors (595393).

21240911 is a wasteful number, since it uses less digits than its factorization.

21240911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1881.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 21240911 is about 4608.7862827430. The cubic root of 21240911 is about 276.9434170463.

The spelling of 21240911 in words is "twenty-one million, two hundred forty thousand, nine hundred eleven".