18617681 has 8 divisors (see below), whose sum is σ = 19624680. Its totient is φ = 17635072.

The previous prime is 18617671. The next prime is 18617689. The reversal of 18617681 is 18671681.

It can be written as a sum of positive squares in 4 ways, for example, as 3094081 + 15523600 = 1759^2 + 3940^2 .

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 18617681 - 2¹⁰ = 18616657 is a prime.

It is a super-2 number, since 2×18617681² = 693236091635522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18617689) 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, 4520 + ... + 7593.

It is an arithmetic number, because the mean of its divisors is an integer number (2453085).

Almost surely, 2^18617681 is an apocalyptic number.

It is an amenable number.

18617681 is a deficient number, since it is larger than the sum of its proper divisors (1006999).

18617681 is a wasteful number, since it uses less digits than its factorization.

18617681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12195.

The product of its digits is 16128, while the sum is 38.

The square root of 18617681 is about 4314.8210855144. The cubic root of 18617681 is about 265.0382334772.

The spelling of 18617681 in words is "eighteen million, six hundred seventeen thousand, six hundred eighty-one".