990681 has 4 divisors (see below), whose sum is σ = 1320912. Its totient is φ = 660452.

The previous prime is 990673. The next prime is 990707. The reversal of 990681 is 186099.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 990681 - 2³ = 990673 is a prime.

It is a super-2 number, since 2×990681² = 1962897687522, which contains 22 as substring.

It is a D-number.

990681 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (990631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 165111 + ... + 165116.

It is an arithmetic number, because the mean of its divisors is an integer number (330228).

2⁹⁹⁰⁶⁸¹ is an apocalyptic number.

It is an amenable number.

990681 is a deficient number, since it is larger than the sum of its proper divisors (330231).

990681 is a wasteful number, since it uses less digits than its factorization.

990681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330230.

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 990681 is about 995.3295936523. The cubic root of 990681 is about 99.6883967091.

The spelling of 990681 in words is "nine hundred ninety thousand, six hundred eighty-one".