8991531 has 12 divisors (see below), whose sum is σ = 13110552. Its totient is φ = 5937696.

The previous prime is 8991529. The next prime is 8991533. The reversal of 8991531 is 1351998.

It is a happy number.

8991531 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (8991529) and next prime (8991533).

It is not a de Polignac number, because 8991531 - 2¹ = 8991529 is a prime.

It is a super-2 number, since 2×8991531² = 161695259447922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (8991533) 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 11 ways as a sum of consecutive naturals, for example, 3706 + ... + 5631.

It is an arithmetic number, because the mean of its divisors is an integer number (1092546).

Almost surely, 2^8991531 is an apocalyptic number.

8991531 is a deficient number, since it is larger than the sum of its proper divisors (4119021).

8991531 is a wasteful number, since it uses less digits than its factorization.

8991531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9450 (or 9447 counting only the distinct ones).

The product of its digits is 9720, while the sum is 36.

The square root of 8991531 is about 2998.5881677883. The cubic root of 8991531 is about 207.9431165333.

The spelling of 8991531 in words is "eight million, nine hundred ninety-one thousand, five hundred thirty-one".