990987 has 4 divisors (see below), whose sum is σ = 1321320. Its totient is φ = 660656.

The previous prime is 990973. The next prime is 990989. The reversal of 990987 is 789099.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 990987 - 2⁶ = 990923 is a prime.

It is a D-number.

It is not an unprimeable number, because it can be changed into a prime (990989) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 165162 + ... + 165167.

It is an arithmetic number, because the mean of its divisors is an integer number (330330).

2⁹⁹⁰⁹⁸⁷ is an apocalyptic number.

990987 is a deficient number, since it is larger than the sum of its proper divisors (330333).

990987 is a wasteful number, since it uses less digits than its factorization.

990987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330332.

The product of its (nonzero) digits is 40824, while the sum is 42.

The square root of 990987 is about 995.4832997092. The cubic root of 990987 is about 99.6986595179.

The spelling of 990987 in words is "nine hundred ninety thousand, nine hundred eighty-seven".