21115333505 has 16 divisors (see below), whose sum is σ = 29574305280. Its totient is φ = 14171019072.

The previous prime is 21115333501. The next prime is 21115333511. The reversal of 21115333505 is 50533351112.

It is a happy number.

It is not a de Polignac number, because 21115333505 - 2² = 21115333501 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21115333501) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6416390 + ... + 6419679.

It is an arithmetic number, because the mean of its divisors is an integer number (1848394080).

Almost surely, 2^21115333505 is an apocalyptic number.

It is an amenable number.

21115333505 is a deficient number, since it is larger than the sum of its proper divisors (8458971775).

21115333505 is a wasteful number, since it uses less digits than its factorization.

21115333505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12836128.

The product of its (nonzero) digits is 6750, while the sum is 29.

Adding to 21115333505 its reverse (50533351112), we get a palindrome (71648684617).

The spelling of 21115333505 in words is "twenty-one billion, one hundred fifteen million, three hundred thirty-three thousand, five hundred five".