9781665 has 16 divisors (see below), whose sum is σ = 15885888. Its totient is φ = 5138496.

The previous prime is 9781661. The next prime is 9781697. The reversal of 9781665 is 5661879.

It is not a de Polignac number, because 9781665 - 2² = 9781661 is a prime.

It is not an unprimeable number, because it can be changed into a prime (9781661) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3862 + ... + 5871.

It is an arithmetic number, because the mean of its divisors is an integer number (992868).

Almost surely, 2^9781665 is an apocalyptic number.

It is an amenable number.

9781665 is a deficient number, since it is larger than the sum of its proper divisors (6104223).

9781665 is a wasteful number, since it uses less digits than its factorization.

9781665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9808.

The product of its digits is 90720, while the sum is 42.

The square root of 9781665 is about 3127.5653470391. The cubic root of 9781665 is about 213.8639555152.

The spelling of 9781665 in words is "nine million, seven hundred eighty-one thousand, six hundred sixty-five".