18987987 has 8 divisors (see below), whose sum is σ = 25356240. Its totient is φ = 12639200.

The previous prime is 18987977. The next prime is 18988003. The reversal of 18987987 is 78978981.

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 18987987 - 2⁴ = 18987971 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18987907) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2412 + ... + 6617.

It is an arithmetic number, because the mean of its divisors is an integer number (3169530).

Almost surely, 2^18987987 is an apocalyptic number.

18987987 is a deficient number, since it is larger than the sum of its proper divisors (6368253).

18987987 is an equidigital number, since it uses as much as digits as its factorization.

18987987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9733.

The product of its digits is 2032128, while the sum is 57.

The square root of 18987987 is about 4357.5207400539. The cubic root of 18987987 is about 266.7839152806.

The spelling of 18987987 in words is "eighteen million, nine hundred eighty-seven thousand, nine hundred eighty-seven".