21115242505 has 64 divisors (see below), whose sum is σ = 30337597440. Its totient is φ = 13804761600.

The previous prime is 21115242497. The next prime is 21115242523. The reversal of 21115242505 is 50524251112.

It is not a de Polignac number, because 21115242505 - 2³ = 21115242497 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 27746325 + ... + 27747085.

It is an arithmetic number, because the mean of its divisors is an integer number (474024960).

Almost surely, 2^21115242505 is an apocalyptic number.

It is an amenable number.

21115242505 is a deficient number, since it is larger than the sum of its proper divisors (9222354935).

21115242505 is a wasteful number, since it uses less digits than its factorization.

21115242505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1150.

The product of its (nonzero) digits is 4000, while the sum is 28.

Adding to 21115242505 its reverse (50524251112), we get a palindrome (71639493617).

The spelling of 21115242505 in words is "twenty-one billion, one hundred fifteen million, two hundred forty-two thousand, five hundred five".