21115005503 has 2 divisors, whose sum is σ = 21115005504. Its totient is φ = 21115005502.

The previous prime is 21115005481. The next prime is 21115005511. The reversal of 21115005503 is 30550051112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21115005503 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21115001503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10557502751 + 10557502752.

It is an arithmetic number, because the mean of its divisors is an integer number (10557502752).

Almost surely, 2^21115005503 is an apocalyptic number.

21115005503 is a deficient number, since it is larger than the sum of its proper divisors (1).

21115005503 is an equidigital number, since it uses as much as digits as its factorization.

21115005503 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 750, while the sum is 23.

Adding to 21115005503 its reverse (30550051112), we get a palindrome (51665056615).

The spelling of 21115005503 in words is "twenty-one billion, one hundred fifteen million, five thousand, five hundred three".