8991161 has 4 divisors (see below), whose sum is σ = 9464400. Its totient is φ = 8517924.

The previous prime is 8991149. The next prime is 8991163. The reversal of 8991161 is 1611998.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 8991161 - 2⁶ = 8991097 is a prime.

It is a super-2 number, since 2×8991161² = 161681952255842, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8991163) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 236591 + ... + 236628.

It is an arithmetic number, because the mean of its divisors is an integer number (2366100).

Almost surely, 2^8991161 is an apocalyptic number.

It is an amenable number.

8991161 is a deficient number, since it is larger than the sum of its proper divisors (473239).

8991161 is a wasteful number, since it uses less digits than its factorization.

8991161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 473238.

The product of its digits is 3888, while the sum is 35.

The square root of 8991161 is about 2998.5264714523. The cubic root of 8991161 is about 207.9402642193.

It can be divided in two parts, 8991 and 161, that multiplied together give a triangular number (1447551 = T₁₇₀₁).

The spelling of 8991161 in words is "eight million, nine hundred ninety-one thousand, one hundred sixty-one".