21316259191 has 4 divisors (see below), whose sum is σ = 21405448800. Its totient is φ = 21227069584.

The previous prime is 21316259189. The next prime is 21316259207. The reversal of 21316259191 is 19195261312.

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 21316259191 - 2¹ = 21316259189 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 (21316259791) 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, 44594446 + ... + 44594923.

It is an arithmetic number, because the mean of its divisors is an integer number (5351362200).

Almost surely, 2^21316259191 is an apocalyptic number.

21316259191 is a deficient number, since it is larger than the sum of its proper divisors (89189609).

21316259191 is an equidigital number, since it uses as much as digits as its factorization.

21316259191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89189608.

The product of its digits is 29160, while the sum is 40.

The spelling of 21316259191 in words is "twenty-one billion, three hundred sixteen million, two hundred fifty-nine thousand, one hundred ninety-one".