27791890681 has 9 divisors (see below), whose sum is σ = 28403796549. Its totient is φ = 27192905244.

The previous prime is 27791890627. The next prime is 27791890699. The reversal of 27791890681 is 18609819772.

The square root of 27791890681 is 166709.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 27791890681 - 2⁹ = 27791890169 is a prime.

It is a super-2 number, since 2×27791890681² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (27791891681) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 7833550 + ... + 7837096.

Almost surely, 2^27791890681 is an apocalyptic number.

27791890681 is the 166709-th square number.

27791890681 is the 83355-th centered octagonal number.

It is an amenable number.

27791890681 is a deficient number, since it is larger than the sum of its proper divisors (611905868).

27791890681 is an frugal number, since it uses more digits than its factorization.

27791890681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7188 (or 3594 counting only the distinct ones).

The product of its (nonzero) digits is 3048192, while the sum is 58.

The spelling of 27791890681 in words is "twenty-seven billion, seven hundred ninety-one million, eight hundred ninety thousand, six hundred eighty-one".