18889993 has 2 divisors, whose sum is σ = 18889994. Its totient is φ = 18889992.

The previous prime is 18889979. The next prime is 18889999. The reversal of 18889993 is 39998881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17749369 + 1140624 = 4213^2 + 1068^2 .

It is a cyclic number.

It is not a de Polignac number, because 18889993 - 2¹⁷ = 18758921 is a prime.

It is not a weakly prime, because it can be changed into another prime (18889999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9444996 + 9444997.

It is an arithmetic number, because the mean of its divisors is an integer number (9444997).

Almost surely, 2^18889993 is an apocalyptic number.

It is an amenable number.

18889993 is a deficient number, since it is larger than the sum of its proper divisors (1).

18889993 is an equidigital number, since it uses as much as digits as its factorization.

18889993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1119744, while the sum is 55.

The square root of 18889993 is about 4346.2619571305. The cubic root of 18889993 is about 266.3241802901.

It can be divided in two parts, 1888 and 9993, that added together give a square (11881 = 109²).

The spelling of 18889993 in words is "eighteen million, eight hundred eighty-nine thousand, nine hundred ninety-three".