18649973 has 2 divisors, whose sum is σ = 18649974. Its totient is φ = 18649972.

The previous prime is 18649937. The next prime is 18649979. The reversal of 18649973 is 37994681.

Together with previous prime (18649937) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13235044 + 5414929 = 3638^2 + 2327^2 .

It is a cyclic number.

It is not a de Polignac number, because 18649973 - 2⁶ = 18649909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18649979) 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 as a sum of consecutive naturals, namely, 9324986 + 9324987.

It is an arithmetic number, because the mean of its divisors is an integer number (9324987).

Almost surely, 2^18649973 is an apocalyptic number.

It is an amenable number.

18649973 is a deficient number, since it is larger than the sum of its proper divisors (1).

18649973 is an equidigital number, since it uses as much as digits as its factorization.

18649973 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 326592, while the sum is 47.

The square root of 18649973 is about 4318.5614502980. The cubic root of 18649973 is about 265.1913794956.

The spelling of 18649973 in words is "eighteen million, six hundred forty-nine thousand, nine hundred seventy-three".