18156949 has 2 divisors, whose sum is σ = 18156950. Its totient is φ = 18156948.

The previous prime is 18156947. The next prime is 18156961. The reversal of 18156949 is 94965181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16957924 + 1199025 = 4118^2 + 1095^2 .

It is an emirp because it is prime and its reverse (94965181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18156949 - 2¹ = 18156947 is a prime.

Together with 18156947, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18156947) 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 as a sum of consecutive naturals, namely, 9078474 + 9078475.

It is an arithmetic number, because the mean of its divisors is an integer number (9078475).

Almost surely, 2^18156949 is an apocalyptic number.

It is an amenable number.

18156949 is a deficient number, since it is larger than the sum of its proper divisors (1).

18156949 is an equidigital number, since it uses as much as digits as its factorization.

18156949 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 77760, while the sum is 43.

The square root of 18156949 is about 4261.0971591833. The cubic root of 18156949 is about 262.8336449846.

The spelling of 18156949 in words is "eighteen million, one hundred fifty-six thousand, nine hundred forty-nine".