990691 has 4 divisors (see below), whose sum is σ = 1066912. Its totient is φ = 914472.

The previous prime is 990673. The next prime is 990707. The reversal of 990691 is 196099.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 196099 = 19 ⋅10321.

It is not a de Polignac number, because 990691 - 2⁹ = 990179 is a prime.

It is a Duffinian number.

990691 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, 38091 + ... + 38116.

It is an arithmetic number, because the mean of its divisors is an integer number (266728).

2⁹⁹⁰⁶⁹¹ is an apocalyptic number.

990691 is a deficient number, since it is larger than the sum of its proper divisors (76221).

990691 is a wasteful number, since it uses less digits than its factorization.

990691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76220.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 990691 is about 995.3346171012. The cubic root of 990691 is about 99.6887321284.

It can be divided in two parts, 990 and 691, that added together give a square (1681 = 41²).

The spelling of 990691 in words is "nine hundred ninety thousand, six hundred ninety-one".