18637649 has 2 divisors, whose sum is σ = 18637650. Its totient is φ = 18637648.

The previous prime is 18637643. The next prime is 18637669. The reversal of 18637649 is 94673681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10758400 + 7879249 = 3280^2 + 2807^2 .

It is a cyclic number.

It is not a de Polignac number, because 18637649 - 2⁸ = 18637393 is a prime.

It is not a weakly prime, because it can be changed into another prime (18637643) 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, 9318824 + 9318825.

It is an arithmetic number, because the mean of its divisors is an integer number (9318825).

Almost surely, 2^18637649 is an apocalyptic number.

It is an amenable number.

18637649 is a deficient number, since it is larger than the sum of its proper divisors (1).

18637649 is an equidigital number, since it uses as much as digits as its factorization.

18637649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 44.

The square root of 18637649 is about 4317.1343504691. The cubic root of 18637649 is about 265.1329533393.

The spelling of 18637649 in words is "eighteen million, six hundred thirty-seven thousand, six hundred forty-nine".