21542431111 has 4 divisors (see below), whose sum is σ = 21600185992. Its totient is φ = 21484676232.

The previous prime is 21542431087. The next prime is 21542431117. The reversal of 21542431111 is 11113424512.

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 21542431111 - 2³¹ = 19394947463 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 (21542431117) 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, 28876881 + ... + 28877626.

It is an arithmetic number, because the mean of its divisors is an integer number (5400046498).

Almost surely, 2^21542431111 is an apocalyptic number.

21542431111 is a deficient number, since it is larger than the sum of its proper divisors (57754881).

21542431111 is an equidigital number, since it uses as much as digits as its factorization.

21542431111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57754880.

The product of its digits is 960, while the sum is 25.

Adding to 21542431111 its reverse (11113424512), we get a palindrome (32655855623).

The spelling of 21542431111 in words is "twenty-one billion, five hundred forty-two million, four hundred thirty-one thousand, one hundred eleven".