18561147877 has 4 divisors (see below), whose sum is σ = 18565528716. Its totient is φ = 18556767040.

The previous prime is 18561147853. The next prime is 18561147883. The reversal of 18561147877 is 77874116581.

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 17682084676 + 879063201 = 132974^2 + 29649^2 .

It is a cyclic number.

It is not a de Polignac number, because 18561147877 - 2⁷ = 18561147749 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 (18561142877) 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, 2184058 + ... + 2192539.

It is an arithmetic number, because the mean of its divisors is an integer number (4641382179).

Almost surely, 2^18561147877 is an apocalyptic number.

It is an amenable number.

18561147877 is a deficient number, since it is larger than the sum of its proper divisors (4380839).

18561147877 is an equidigital number, since it uses as much as digits as its factorization.

18561147877 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4380838.

The product of its digits is 2634240, while the sum is 55.

The spelling of 18561147877 in words is "eighteen billion, five hundred sixty-one million, one hundred forty-seven thousand, eight hundred seventy-seven".