991660847 has 8 divisors (see below), whose sum is σ = 1095646176. Its totient is φ = 892748032.

The previous prime is 991660811. The next prime is 991660853. The reversal of 991660847 is 748066199.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 991660847 - 2¹⁴ = 991644463 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 991660795 and 991660804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991660877) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1267718 + ... + 1268499.

It is an arithmetic number, because the mean of its divisors is an integer number (136955772).

Almost surely, 2^991660847 is an apocalyptic number.

991660847 is a deficient number, since it is larger than the sum of its proper divisors (103985329).

991660847 is a wasteful number, since it uses less digits than its factorization.

991660847 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2536257.

The product of its (nonzero) digits is 653184, while the sum is 50.

The square root of 991660847 is about 31490.6469765230. The cubic root of 991660847 is about 997.2125195054.

The spelling of 991660847 in words is "nine hundred ninety-one million, six hundred sixty thousand, eight hundred forty-seven".