18081785 has 4 divisors (see below), whose sum is σ = 21698148. Its totient is φ = 14465424.

The previous prime is 18081781. The next prime is 18081821. The reversal of 18081785 is 58718081.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2621161 + 15460624 = 1619^2 + 3932^2 .

It is a cyclic number.

It is not a de Polignac number, because 18081785 - 2² = 18081781 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18081781) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1808174 + ... + 1808183.

It is an arithmetic number, because the mean of its divisors is an integer number (5424537).

Almost surely, 2^18081785 is an apocalyptic number.

It is an amenable number.

18081785 is a deficient number, since it is larger than the sum of its proper divisors (3616363).

18081785 is an equidigital number, since it uses as much as digits as its factorization.

18081785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3616362.

The product of its (nonzero) digits is 17920, while the sum is 38.

The square root of 18081785 is about 4252.2682182572. The cubic root of 18081785 is about 262.4704607728.

The spelling of 18081785 in words is "eighteen million, eighty-one thousand, seven hundred eighty-five".