18681605 has 8 divisors (see below), whose sum is σ = 22448664. Its totient is φ = 14924800.

The previous prime is 18681577. The next prime is 18681613. The reversal of 18681605 is 50618681.

It can be written as a sum of positive squares in 4 ways, for example, as 3928324 + 14753281 = 1982^2 + 3841^2 .

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

It is not a de Polignac number, because 18681605 - 2⁸ = 18681349 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2285 + ... + 6525.

It is an arithmetic number, because the mean of its divisors is an integer number (2806083).

Almost surely, 2^18681605 is an apocalyptic number.

It is an amenable number.

18681605 is a deficient number, since it is larger than the sum of its proper divisors (3767059).

18681605 is an equidigital number, since it uses as much as digits as its factorization.

18681605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5127.

The product of its (nonzero) digits is 11520, while the sum is 35.

The square root of 18681605 is about 4322.2222293630. Note that the first 5 decimals coincide. The cubic root of 18681605 is about 265.3412241382.

The spelling of 18681605 in words is "eighteen million, six hundred eighty-one thousand, six hundred five".