21152131111 has 4 divisors (see below), whose sum is σ = 21152425392. Its totient is φ = 21151836832.

The previous prime is 21152131097. The next prime is 21152131129. The reversal of 21152131111 is 11113125112.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21152131111 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 (21152131151) 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, 40095 + ... + 209551.

It is an arithmetic number, because the mean of its divisors is an integer number (5288106348).

Almost surely, 2^21152131111 is an apocalyptic number.

21152131111 is a deficient number, since it is larger than the sum of its proper divisors (294281).

21152131111 is a wasteful number, since it uses less digits than its factorization.

21152131111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 294280.

The product of its digits is 60, while the sum is 19.

Adding to 21152131111 its reverse (11113125112), we get a palindrome (32265256223).

The spelling of 21152131111 in words is "twenty-one billion, one hundred fifty-two million, one hundred thirty-one thousand, one hundred eleven".