21205502513 has 16 divisors (see below), whose sum is σ = 23277191616. Its totient is φ = 19197048000.

The previous prime is 21205502509. The next prime is 21205502537. The reversal of 21205502513 is 31520550212.

It is not a de Polignac number, because 21205502513 - 2² = 21205502509 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21205502573) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2235206 + ... + 2244672.

It is an arithmetic number, because the mean of its divisors is an integer number (1454824476).

Almost surely, 2^21205502513 is an apocalyptic number.

It is an amenable number.

21205502513 is a deficient number, since it is larger than the sum of its proper divisors (2071689103).

21205502513 is a wasteful number, since it uses less digits than its factorization.

21205502513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12784.

The product of its (nonzero) digits is 3000, while the sum is 26.

The spelling of 21205502513 in words is "twenty-one billion, two hundred five million, five hundred two thousand, five hundred thirteen".