21127168687 has 4 divisors (see below), whose sum is σ = 21132015400. Its totient is φ = 21122321976.

The previous prime is 21127168661. The next prime is 21127168717. The reversal of 21127168687 is 78686172112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21127168687 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21127168687.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21127168487) 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, 2416812 + ... + 2425537.

It is an arithmetic number, because the mean of its divisors is an integer number (5283003850).

Almost surely, 2^21127168687 is an apocalyptic number.

21127168687 is a deficient number, since it is larger than the sum of its proper divisors (4846713).

21127168687 is an equidigital number, since it uses as much as digits as its factorization.

21127168687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4846712.

The product of its digits is 451584, while the sum is 49.

The spelling of 21127168687 in words is "twenty-one billion, one hundred twenty-seven million, one hundred sixty-eight thousand, six hundred eighty-seven".