18989987 has 8 divisors (see below), whose sum is σ = 20072400. Its totient is φ = 17915904.

The previous prime is 18989959. The next prime is 18990017. The reversal of 18989987 is 78998981.

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 18989987 - 2⁶ = 18989923 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18989947) 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, 2939 + ... + 6827.

It is an arithmetic number, because the mean of its divisors is an integer number (2509050).

Almost surely, 2^18989987 is an apocalyptic number.

18989987 is a deficient number, since it is larger than the sum of its proper divisors (1082413).

18989987 is a wasteful number, since it uses less digits than its factorization.

18989987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4165.

The product of its digits is 2612736, while the sum is 59.

The square root of 18989987 is about 4357.7502223051. The cubic root of 18989987 is about 266.7932817131.

The spelling of 18989987 in words is "eighteen million, nine hundred eighty-nine thousand, nine hundred eighty-seven".