21115131321511 has 4 divisors (see below), whose sum is σ = 21115240088800. Its totient is φ = 21115022554224.

The previous prime is 21115131321503. The next prime is 21115131321577. The reversal of 21115131321511 is 11512313151112.

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 21115131321511 - 2³ = 21115131321503 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21115131321511.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115131321611) 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, 54091926 + ... + 54480883.

It is an arithmetic number, because the mean of its divisors is an integer number (5278810022200).

Almost surely, 2^{21115131321511} is an apocalyptic number.

21115131321511 is a deficient number, since it is larger than the sum of its proper divisors (108767289).

21115131321511 is a wasteful number, since it uses less digits than its factorization.

21115131321511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108767288.

The product of its digits is 900, while the sum is 28.

Adding to 21115131321511 its reverse (11512313151112), we get a palindrome (32627444472623).

The spelling of 21115131321511 in words is "twenty-one trillion, one hundred fifteen billion, one hundred thirty-one million, three hundred twenty-one thousand, five hundred eleven".