18979999 has 2 divisors, whose sum is σ = 18980000. Its totient is φ = 18979998.

The previous prime is 18979957. The next prime is 18980011. The reversal of 18979999 is 99997981.

It is a strong prime.

It is an emirp because it is prime and its reverse (99997981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18979999 - 2⁹ = 18979487 is a prime.

18979999 is a modest number, since divided by 9999 gives 1897 as remainder.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18976999) 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, 9489999 + 9490000.

It is an arithmetic number, because the mean of its divisors is an integer number (9490000).

Almost surely, 2^18979999 is an apocalyptic number.

18979999 is a deficient number, since it is larger than the sum of its proper divisors (1).

18979999 is an equidigital number, since it uses as much as digits as its factorization.

18979999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3306744, while the sum is 61.

The square root of 18979999 is about 4356.6040673901. The cubic root of 18979999 is about 266.7464991883.

The spelling of 18979999 in words is "eighteen million, nine hundred seventy-nine thousand, nine hundred ninety-nine".