18205681 has 8 divisors (see below), whose sum is σ = 20084904. Its totient is φ = 16394880.

The previous prime is 18205619. The next prime is 18205687. The reversal of 18205681 is 18650281.

It can be written as a sum of positive squares in 4 ways, for example, as 58081 + 18147600 = 241^2 + 4260^2 .

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 18205681 - 2⁹ = 18205169 is a prime.

It is a super-2 number, since 2×18205681² = 662893641347522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18205687) 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, 16546 + ... + 17611.

It is an arithmetic number, because the mean of its divisors is an integer number (2510613).

Almost surely, 2^18205681 is an apocalyptic number.

It is an amenable number.

18205681 is a deficient number, since it is larger than the sum of its proper divisors (1879223).

18205681 is a wasteful number, since it uses less digits than its factorization.

18205681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34211.

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 18205681 is about 4266.8115730601. The cubic root of 18205681 is about 263.0685773932.

The spelling of 18205681 in words is "eighteen million, two hundred five thousand, six hundred eighty-one".