991000000166 has 24 divisors (see below), whose sum is σ = 1634050906320. Its totient is φ = 450418866480.

The previous prime is 991000000139. The next prime is 991000000181. The reversal of 991000000166 is 661000000199.

It is a happy number.

991000000166 is a strobogrammatic number because it is the same when read upside-down.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3028880 + ... + 3340076.

It is an arithmetic number, because the mean of its divisors is an integer number (68085454430).

Almost surely, 2^991000000166 is an apocalyptic number.

991000000166 is a deficient number, since it is larger than the sum of its proper divisors (643050906154).

991000000166 is a wasteful number, since it uses less digits than its factorization.

991000000166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 324380 (or 324369 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 32.

The spelling of 991000000166 in words is "nine hundred ninety-one billion, one hundred sixty-six", and thus it is an aban number.