991090 has 8 divisors (see below), whose sum is σ = 1783980. Its totient is φ = 396432.

The previous prime is 991079. The next prime is 991091. The reversal of 991090 is 90199.

It can be written as a sum of positive squares in 2 ways, for example, as 986049 + 5041 = 993^2 + 71^2 .

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

It is not an unprimeable number, because it can be changed into a prime (991091) by changing a digit.

991090 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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, 49545 + ... + 49564.

2⁹⁹¹⁰⁹⁰ is an apocalyptic number.

991090 is a deficient number, since it is larger than the sum of its proper divisors (792890).

991090 is a wasteful number, since it uses less digits than its factorization.

991090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99116.

The product of its (nonzero) digits is 729, while the sum is 28.

The square root of 991090 is about 995.5350320305. The cubic root of 991090 is about 99.7021135175.

It can be divided in two parts, 9910 and 90, that added together give a 4-th power (10000 = 10⁴).

The spelling of 991090 in words is "nine hundred ninety-one thousand, ninety".