18991879 has 2 divisors, whose sum is σ = 18991880. Its totient is φ = 18991878.

The previous prime is 18991867. The next prime is 18991891. The reversal of 18991879 is 97819981.

It is a balanced prime because it is at equal distance from previous prime (18991867) and next prime (18991891).

It is a cyclic number.

It is not a de Polignac number, because 18991879 - 2²¹ = 16894727 is a prime.

It is a super-3 number, since 3×18991879³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18992879) 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, 9495939 + 9495940.

It is an arithmetic number, because the mean of its divisors is an integer number (9495940).

Almost surely, 2^18991879 is an apocalyptic number.

18991879 is a deficient number, since it is larger than the sum of its proper divisors (1).

18991879 is an equidigital number, since it uses as much as digits as its factorization.

18991879 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 326592, while the sum is 52.

The square root of 18991879 is about 4357.9673013918. The cubic root of 18991879 is about 266.8021417530.

The spelling of 18991879 in words is "eighteen million, nine hundred ninety-one thousand, eight hundred seventy-nine".