18540661 has 4 divisors (see below), whose sum is σ = 18606924. Its totient is φ = 18474400.

The previous prime is 18540649. The next prime is 18540667. The reversal of 18540661 is 16604581.

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 13727025 + 4813636 = 3705^2 + 2194^2 .

It is a cyclic number.

It is not a de Polignac number, because 18540661 - 2¹¹ = 18538613 is a prime.

It is a super-2 number, since 2×18540661² = 687512220633842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18540667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32710 + ... + 33271.

It is an arithmetic number, because the mean of its divisors is an integer number (4651731).

Almost surely, 2^18540661 is an apocalyptic number.

It is an amenable number.

18540661 is a deficient number, since it is larger than the sum of its proper divisors (66263).

18540661 is an equidigital number, since it uses as much as digits as its factorization.

18540661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66262.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 18540661 is about 4305.8867843918. The cubic root of 18540661 is about 264.6722469903.

The spelling of 18540661 in words is "eighteen million, five hundred forty thousand, six hundred sixty-one".