18381009181 has 4 divisors (see below), whose sum is σ = 18382038364. Its totient is φ = 18379980000.

The previous prime is 18381009173. The next prime is 18381009191. The reversal of 18381009181 is 18190018381.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18190018381 = 89 ⋅204382229.

It can be written as a sum of positive squares in 2 ways, for example, as 15414464025 + 2966545156 = 124155^2 + 54466^2 .

It is a cyclic number.

It is not a de Polignac number, because 18381009181 - 2³ = 18381009173 is a prime.

It is a super-2 number, since 2×18381009181² (a number of 21 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 (18381009121) 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, 487320 + ... + 523681.

It is an arithmetic number, because the mean of its divisors is an integer number (4595509591).

Almost surely, 2^18381009181 is an apocalyptic number.

It is an amenable number.

18381009181 is a deficient number, since it is larger than the sum of its proper divisors (1029183).

18381009181 is a wasteful number, since it uses less digits than its factorization.

18381009181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1029182.

The product of its (nonzero) digits is 13824, while the sum is 40.

The spelling of 18381009181 in words is "eighteen billion, three hundred eighty-one million, nine thousand, one hundred eighty-one".