27771641581 has 4 divisors (see below), whose sum is σ = 27773840512. Its totient is φ = 27769442652.

The previous prime is 27771641549. The next prime is 27771641591. The reversal of 27771641581 is 18514617772.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 27771641581 - 2⁵ = 27771641549 is a prime.

It is a super-2 number, since 2×27771641581² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (27771641501) 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, 1080411 + ... + 1105816.

It is an arithmetic number, because the mean of its divisors is an integer number (6943460128).

Almost surely, 2^27771641581 is an apocalyptic number.

It is an amenable number.

27771641581 is a deficient number, since it is larger than the sum of its proper divisors (2198931).

27771641581 is a wasteful number, since it uses less digits than its factorization.

27771641581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2198930.

The product of its digits is 658560, while the sum is 49.

The spelling of 27771641581 in words is "twenty-seven billion, seven hundred seventy-one million, six hundred forty-one thousand, five hundred eighty-one".