9991666 has 8 divisors (see below), whose sum is σ = 15270444.
Its totient is φ = 4901520.
The previous prime is 9991649. The next prime is 9991669. The reversal of 9991666 is 6661999.
It can be written as a sum of positive squares in 2 ways, for example, as 8288641 + 1703025 = 2879^2 + 1305^2
It is a sphenic number, since it is the product of 3 distinct primes.
9991666 is a strobogrammatic number because it is the same when read upside-down.
It is not an unprimeable number, because it can be changed into a prime (9991669) 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, 47025 + ... + 47236.
Almost surely, 29991666 is an apocalyptic number.
9991666 is a deficient number, since it is larger than the sum of its proper divisors (5278778).
9991666 is a wasteful number, since it uses less digits than its factorization.
9991666 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 94316.
The product of its digits is 157464, while the sum is 46.
The square root of 9991666 is about 3160.9596644057.
The cubic root of 9991666 is about 215.3836021734.
The spelling of 9991666 in words is "nine million, nine hundred ninety-one thousand, six hundred sixty-six".