18681681 has 8 divisors (see below), whose sum is σ = 25992000. Its totient is φ = 11912912.

The previous prime is 18681671. The next prime is 18681697. The reversal of 18681681 is 18618681.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18681681 - 2¹³ = 18673489 is a prime.

It is a super-2 number, since 2×18681681² = 698010409971522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18681661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 135306 + ... + 135443.

It is an arithmetic number, because the mean of its divisors is an integer number (3249000).

Almost surely, 2^18681681 is an apocalyptic number.

It is an amenable number.

18681681 is a deficient number, since it is larger than the sum of its proper divisors (7310319).

18681681 is a wasteful number, since it uses less digits than its factorization.

18681681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270775.

The product of its digits is 18432, while the sum is 39.

The square root of 18681681 is about 4322.2310211279. The cubic root of 18681681 is about 265.3415839557.

The spelling of 18681681 in words is "eighteen million, six hundred eighty-one thousand, six hundred eighty-one".