991655 has 16 divisors (see below), whose sum is σ = 1408320. Its totient is φ = 655872.

The previous prime is 991651. The next prime is 991663. The reversal of 991655 is 556199.

It is not a de Polignac number, because 991655 - 2² = 991651 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35).

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 991655.

It is not an unprimeable number, because it can be changed into a prime (991651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 527 + ... + 1503.

It is an arithmetic number, because the mean of its divisors is an integer number (88020).

2⁹⁹¹⁶⁵⁵ is an apocalyptic number.

991655 is a deficient number, since it is larger than the sum of its proper divisors (416665).

991655 is a wasteful number, since it uses less digits than its factorization.

991655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1018.

The product of its digits is 12150, while the sum is 35.

The square root of 991655 is about 995.8187586102. The cubic root of 991655 is about 99.7210559590.

The spelling of 991655 in words is "nine hundred ninety-one thousand, six hundred fifty-five".