18729989 has 8 divisors (see below), whose sum is σ = 19503960. Its totient is φ = 17971200.

The previous prime is 18729979. The next prime is 18730001. The reversal of 18729989 is 98992781.

18729989 = T₄₉₂ + T₄₉₃ + ... + T₆₁₃.

It can be written as a sum of positive squares in 4 ways, for example, as 667489 + 18062500 = 817^2 + 4250^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18729989 - 2¹² = 18725893 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18729989.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18729929) 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 in 7 ways as a sum of consecutive naturals, for example, 1244 + ... + 6245.

It is an arithmetic number, because the mean of its divisors is an integer number (2437995).

Almost surely, 2^18729989 is an apocalyptic number.

It is an amenable number.

18729989 is a deficient number, since it is larger than the sum of its proper divisors (773971).

18729989 is an equidigital number, since it uses as much as digits as its factorization.

18729989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7591.

The product of its digits is 653184, while the sum is 53.

The square root of 18729989 is about 4327.8157308277. The cubic root of 18729989 is about 265.5700981618.

The spelling of 18729989 in words is "eighteen million, seven hundred twenty-nine thousand, nine hundred eighty-nine".