18255661 has 4 divisors (see below), whose sum is σ = 18389052. Its totient is φ = 18122272.

The previous prime is 18255659. The next prime is 18255707. The reversal of 18255661 is 16655281.

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: 16655281 = 787 ⋅21163.

It can be written as a sum of positive squares in 2 ways, for example, as 14394436 + 3861225 = 3794^2 + 1965^2 .

It is a cyclic number.

It is not a de Polignac number, because 18255661 - 2¹ = 18255659 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 (18255631) 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, 66490 + ... + 66763.

It is an arithmetic number, because the mean of its divisors is an integer number (4597263).

Almost surely, 2^18255661 is an apocalyptic number.

It is an amenable number.

18255661 is a deficient number, since it is larger than the sum of its proper divisors (133391).

18255661 is a wasteful number, since it uses less digits than its factorization.

18255661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133390.

The product of its digits is 14400, while the sum is 34.

The square root of 18255661 is about 4272.6643912201. The cubic root of 18255661 is about 263.3090912185.

The spelling of 18255661 in words is "eighteen million, two hundred fifty-five thousand, six hundred sixty-one".