27991817433491 has 4 divisors (see below), whose sum is σ = 28009500200352. Its totient is φ = 27974134666632.

The previous prime is 27991817433389. The next prime is 27991817433509. The reversal of 27991817433491 is 19433471819972.

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 27991817433491 - 2²⁶ = 27991750324627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (27991817453491) 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, 8841381056 + ... + 8841384221.

It is an arithmetic number, because the mean of its divisors is an integer number (7002375050088).

Almost surely, 2^{27991817433491} is an apocalyptic number.

27991817433491 is a deficient number, since it is larger than the sum of its proper divisors (17682766861).

27991817433491 is a wasteful number, since it uses less digits than its factorization.

27991817433491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17682766860.

The product of its digits is 82301184, while the sum is 68.

The spelling of 27991817433491 in words is "twenty-seven trillion, nine hundred ninety-one billion, eight hundred seventeen million, four hundred thirty-three thousand, four hundred ninety-one".