27777451661 has 4 divisors (see below), whose sum is σ = 28454950524. Its totient is φ = 27099952800.

The previous prime is 27777451649. The next prime is 27777451703. The reversal of 27777451661 is 16615477772.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5883810436 + 21893641225 = 76706^2 + 147965^2 .

It is a cyclic number.

It is not a de Polignac number, because 27777451661 - 2²⁶ = 27710342797 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 (27777457661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 338749370 + ... + 338749451.

It is an arithmetic number, because the mean of its divisors is an integer number (7113737631).

Almost surely, 2^27777451661 is an apocalyptic number.

It is an amenable number.

27777451661 is a deficient number, since it is larger than the sum of its proper divisors (677498863).

27777451661 is an equidigital number, since it uses as much as digits as its factorization.

27777451661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 677498862.

The product of its digits is 3457440, while the sum is 53.

The spelling of 27777451661 in words is "twenty-seven billion, seven hundred seventy-seven million, four hundred fifty-one thousand, six hundred sixty-one".