21169038687 has 4 divisors (see below), whose sum is σ = 28225384920. Its totient is φ = 14112692456.

The previous prime is 21169038661. The next prime is 21169038739. The reversal of 21169038687 is 78683096112.

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

It is a cyclic number.

It is not a de Polignac number, because 21169038687 - 2²² = 21164844383 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21169038487) 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, 3528173112 + ... + 3528173117.

It is an arithmetic number, because the mean of its divisors is an integer number (7056346230).

Almost surely, 2^21169038687 is an apocalyptic number.

21169038687 is a deficient number, since it is larger than the sum of its proper divisors (7056346233).

21169038687 is an equidigital number, since it uses as much as digits as its factorization.

21169038687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7056346232.

The product of its (nonzero) digits is 870912, while the sum is 51.

The spelling of 21169038687 in words is "twenty-one billion, one hundred sixty-nine million, thirty-eight thousand, six hundred eighty-seven".