20687368517 has 4 divisors (see below), whose sum is σ = 20687663040. Its totient is φ = 20687073996.

The previous prime is 20687368421. The next prime is 20687368523. The reversal of 20687368517 is 71586378602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20687368517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20687368547) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26234 + ... + 205092.

It is an arithmetic number, because the mean of its divisors is an integer number (5171915760).

Almost surely, 2^20687368517 is an apocalyptic number.

It is an amenable number.

20687368517 is a deficient number, since it is larger than the sum of its proper divisors (294523).

20687368517 is a wasteful number, since it uses less digits than its factorization.

20687368517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 294522.

The product of its (nonzero) digits is 3386880, while the sum is 53.

The spelling of 20687368517 in words is "twenty billion, six hundred eighty-seven million, three hundred sixty-eight thousand, five hundred seventeen".