18222561 has 24 divisors (see below), whose sum is σ = 30700800. Its totient is φ = 10411128.

The previous prime is 18222559. The next prime is 18222571. The reversal of 18222561 is 16522281.

It is a happy number.

18222561 is a `hidden beast` number, since 1 + 82 + 22 + 561 = 666.

It is not a de Polignac number, because 18222561 - 2¹ = 18222559 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (18222541) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 136 + ... + 6038.

It is an arithmetic number, because the mean of its divisors is an integer number (1279200).

Almost surely, 2^18222561 is an apocalyptic number.

It is an amenable number.

18222561 is a deficient number, since it is larger than the sum of its proper divisors (12478239).

18222561 is an equidigital number, since it uses as much as digits as its factorization.

18222561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5930 (or 5913 counting only the distinct ones).

The product of its digits is 1920, while the sum is 27.

The square root of 18222561 is about 4268.7891725875. The cubic root of 18222561 is about 263.1498565257.

The spelling of 18222561 in words is "eighteen million, two hundred twenty-two thousand, five hundred sixty-one".