18781366081 has 4 divisors (see below), whose sum is σ = 18794419200. Its totient is φ = 18768312964.

The previous prime is 18781366073. The next prime is 18781366103. The reversal of 18781366081 is 18066318781.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18066318781 = 7 ⋅2580902683.

It is a cyclic number.

It is not a de Polignac number, because 18781366081 - 2³ = 18781366073 is a prime.

It is a super-2 number, since 2×18781366081² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18781366181) 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, 6524401 + ... + 6527278.

It is an arithmetic number, because the mean of its divisors is an integer number (4698604800).

Almost surely, 2^18781366081 is an apocalyptic number.

It is an amenable number.

18781366081 is a deficient number, since it is larger than the sum of its proper divisors (13053119).

18781366081 is a wasteful number, since it uses less digits than its factorization.

18781366081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13053118.

The product of its (nonzero) digits is 387072, while the sum is 49.

The spelling of 18781366081 in words is "eighteen billion, seven hundred eighty-one million, three hundred sixty-six thousand, eighty-one".