18611681 has 8 divisors (see below), whose sum is σ = 20514144. Its totient is φ = 16744320.

The previous prime is 18611657. The next prime is 18611693.

18611681 is nontrivially palindromic in base 10.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18611681 is a prime.

It is a super-2 number, since 2×18611681² = 692789339291522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18611611) 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, 7655 + ... + 9788.

It is an arithmetic number, because the mean of its divisors is an integer number (2564268).

Almost surely, 2^18611681 is an apocalyptic number.

18611681 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18611681 is a deficient number, since it is larger than the sum of its proper divisors (1902463).

18611681 is a wasteful number, since it uses less digits than its factorization.

18611681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17551.

The product of its digits is 2304, while the sum is 32.

The square root of 18611681 is about 4314.1257515283. The cubic root of 18611681 is about 265.0097587483.

The spelling of 18611681 in words is "eighteen million, six hundred eleven thousand, six hundred eighty-one".