991667 has 12 divisors (see below), whose sum is σ = 1088136. Its totient is φ = 902880.

The previous prime is 991663. The next prime is 991693. The reversal of 991667 is 766199.

It is not a de Polignac number, because 991667 - 2² = 991663 is a prime.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 991667.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991667.

It is not an unprimeable number, because it can be changed into a prime (991663) 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 11 ways as a sum of consecutive naturals, for example, 14768 + ... + 14834.

It is an arithmetic number, because the mean of its divisors is an integer number (90678).

2⁹⁹¹⁶⁶⁷ is an apocalyptic number.

991667 is a deficient number, since it is larger than the sum of its proper divisors (96469).

991667 is a wasteful number, since it uses less digits than its factorization.

991667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146 (or 127 counting only the distinct ones).

The product of its digits is 20412, while the sum is 38.

The square root of 991667 is about 995.8247837848. The cubic root of 991667 is about 99.7214581983.

The spelling of 991667 in words is "nine hundred ninety-one thousand, six hundred sixty-seven".