991671009 has 16 divisors (see below), whose sum is σ = 1590650880. Its totient is φ = 536844240.

The previous prime is 991671007. The next prime is 991671017. The reversal of 991671009 is 900176199.

It is not a de Polignac number, because 991671009 - 2¹ = 991671007 is a prime.

It is a super-2 number, since 2×991671009² = 1966822780182156162, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (991671007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1242297 + ... + 1243094.

It is an arithmetic number, because the mean of its divisors is an integer number (99415680).

Almost surely, 2^991671009 is an apocalyptic number.

It is an amenable number.

991671009 is a deficient number, since it is larger than the sum of its proper divisors (598979871).

991671009 is a wasteful number, since it uses less digits than its factorization.

991671009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2485420.

The product of its (nonzero) digits is 30618, while the sum is 42.

The square root of 991671009 is about 31490.8083256051. The cubic root of 991671009 is about 997.2159257906.

The spelling of 991671009 in words is "nine hundred ninety-one million, six hundred seventy-one thousand, nine".