1987989 has 8 divisors (see below), whose sum is σ = 2790240. Its totient is φ = 1255536.

The previous prime is 1987987. The next prime is 1987991. The reversal of 1987989 is 9897891.

It is an interprime number because it is at equal distance from previous prime (1987987) and next prime (1987991).

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

It is not a de Polignac number, because 1987989 - 2¹ = 1987987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1987981) 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, 17382 + ... + 17495.

It is an arithmetic number, because the mean of its divisors is an integer number (348780).

2^1987989 is an apocalyptic number.

1987989 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

1987989 is a deficient number, since it is larger than the sum of its proper divisors (802251).

1987989 is a wasteful number, since it uses less digits than its factorization.

1987989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34899.

The product of its digits is 326592, while the sum is 51.

The square root of 1987989 is about 1409.9606377484. The cubic root of 1987989 is about 125.7393832099.

The spelling of 1987989 in words is "one million, nine hundred eighty-seven thousand, nine hundred eighty-nine".