991708109 has 12 divisors (see below), whose sum is σ = 1155960000. Its totient is φ = 848311128.

The previous prime is 991708103. The next prime is 991708111. The reversal of 991708109 is 901807199.

It is not a de Polignac number, because 991708109 - 2⁸ = 991707853 is a prime.

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 991708109.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991708103) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4172 + ... + 44730.

It is an arithmetic number, because the mean of its divisors is an integer number (96330000).

Almost surely, 2^991708109 is an apocalyptic number.

It is an amenable number.

991708109 is a deficient number, since it is larger than the sum of its proper divisors (164251891).

991708109 is a wasteful number, since it uses less digits than its factorization.

991708109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41072 (or 41065 counting only the distinct ones).

The product of its (nonzero) digits is 40824, while the sum is 44.

The square root of 991708109 is about 31491.3973808721. The cubic root of 991708109 is about 997.2283614503.

The spelling of 991708109 in words is "nine hundred ninety-one million, seven hundred eight thousand, one hundred nine".