21240443111 has 4 divisors (see below), whose sum is σ = 21240814800. Its totient is φ = 21240071424.

The previous prime is 21240443101. The next prime is 21240443123. The reversal of 21240443111 is 11134404212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21240443111 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 (21240443101) 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, 80051 + ... + 221108.

It is an arithmetic number, because the mean of its divisors is an integer number (5310203700).

Almost surely, 2^21240443111 is an apocalyptic number.

21240443111 is a deficient number, since it is larger than the sum of its proper divisors (371689).

21240443111 is an equidigital number, since it uses as much as digits as its factorization.

21240443111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 371688.

The product of its (nonzero) digits is 768, while the sum is 23.

Adding to 21240443111 its reverse (11134404212), we get a palindrome (32374847323).

The spelling of 21240443111 in words is "twenty-one billion, two hundred forty million, four hundred forty-three thousand, one hundred eleven".