917990 has 16 divisors (see below), whose sum is σ = 1693440. Its totient is φ = 358080.

The previous prime is 917971. The next prime is 917993. The reversal of 917990 is 99719.

It is a happy number.

It is a plaindrome in base 11.

It is a self number, because there is not a number n which added to its sum of digits gives 917990.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 917990.

It is not an unprimeable number, because it can be changed into a prime (917993) by changing a digit.

917990 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 710 + ... + 1529.

It is an arithmetic number, because the mean of its divisors is an integer number (105840).

2⁹¹⁷⁹⁹⁰ is an apocalyptic number.

917990 is a deficient number, since it is larger than the sum of its proper divisors (775450).

917990 is a wasteful number, since it uses less digits than its factorization.

917990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2287.

The product of its (nonzero) digits is 5103, while the sum is 35.

The square root of 917990 is about 958.1179468103. The cubic root of 917990 is about 97.1880011382.

The spelling of 917990 in words is "nine hundred seventeen thousand, nine hundred ninety".