18090661 has 4 divisors (see below), whose sum is σ = 18099424. Its totient is φ = 18081900.

The previous prime is 18090643. The next prime is 18090689. The reversal of 18090661 is 16609081.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 16609081 = 409 ⋅40609.

It is a cyclic number.

It is not a de Polignac number, because 18090661 - 2¹¹ = 18088613 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 (18090691) 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, 616 + ... + 6046.

It is an arithmetic number, because the mean of its divisors is an integer number (4524856).

Almost surely, 2^18090661 is an apocalyptic number.

It is an amenable number.

18090661 is a deficient number, since it is larger than the sum of its proper divisors (8763).

18090661 is an equidigital number, since it uses as much as digits as its factorization.

18090661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8762.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 18090661 is about 4253.3117684929. The cubic root of 18090661 is about 262.5134009787.

The spelling of 18090661 in words is "eighteen million, ninety thousand, six hundred sixty-one".