18345661 has 4 divisors (see below), whose sum is σ = 18978300. Its totient is φ = 17713024.

The previous prime is 18345653. The next prime is 18345667. The reversal of 18345661 is 16654381.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16654381 = 29 ⋅574289.

It can be written as a sum of positive squares in 2 ways, for example, as 13461561 + 4884100 = 3669^2 + 2210^2 .

It is a cyclic number.

It is not a de Polignac number, because 18345661 - 2³ = 18345653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18345667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 316276 + ... + 316333.

It is an arithmetic number, because the mean of its divisors is an integer number (4744575).

Almost surely, 2^18345661 is an apocalyptic number.

It is an amenable number.

18345661 is a deficient number, since it is larger than the sum of its proper divisors (632639).

18345661 is an equidigital number, since it uses as much as digits as its factorization.

18345661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 632638.

The product of its digits is 17280, while the sum is 34.

The square root of 18345661 is about 4283.1835122955. The cubic root of 18345661 is about 263.7410847297.

The spelling of 18345661 in words is "eighteen million, three hundred forty-five thousand, six hundred sixty-one".