21013132505 has 8 divisors (see below), whose sum is σ = 25216647624. Its totient is φ = 16809913600.

The previous prime is 21013132471. The next prime is 21013132519. The reversal of 21013132505 is 50523131012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 12026850889 + 8986281616 = 109667^2 + 94796^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21013132505 - 2⁸ = 21013132249 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 136385 + ... + 246225.

It is an arithmetic number, because the mean of its divisors is an integer number (3152080953).

Almost surely, 2^21013132505 is an apocalyptic number.

It is an amenable number.

21013132505 is a deficient number, since it is larger than the sum of its proper divisors (4203515119).

21013132505 is a wasteful number, since it uses less digits than its factorization.

21013132505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148107.

The product of its (nonzero) digits is 900, while the sum is 23.

Adding to 21013132505 its reverse (50523131012), we get a palindrome (71536263517).

The spelling of 21013132505 in words is "twenty-one billion, thirteen million, one hundred thirty-two thousand, five hundred five".