9881581 has 4 divisors (see below), whose sum is σ = 9992700. Its totient is φ = 9770464.

The previous prime is 9881569. The next prime is 9881593. The reversal of 9881581 is 1851889.

9881581 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1851889 = 13 ⋅142453.

It is an interprime number because it is at equal distance from previous prime (9881569) and next prime (9881593).

It can be written as a sum of positive squares in 2 ways, for example, as 1232100 + 8649481 = 1110^2 + 2941^2 .

It is a cyclic number.

It is not a de Polignac number, because 9881581 - 2⁷ = 9881453 is a prime.

It is a super-2 number, since 2×9881581² = 195291286119122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9881551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55426 + ... + 55603.

It is an arithmetic number, because the mean of its divisors is an integer number (2498175).

Almost surely, 2^9881581 is an apocalyptic number.

It is an amenable number.

9881581 is a deficient number, since it is larger than the sum of its proper divisors (111119).

9881581 is a wasteful number, since it uses less digits than its factorization.

9881581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111118.

The product of its digits is 23040, while the sum is 40.

The square root of 9881581 is about 3143.4982105928. The cubic root of 9881581 is about 214.5896698750.

It can be divided in two parts, 988 and 1581, that multiplied together give a triangular number (1562028 = T₁₇₆₇).

The spelling of 9881581 in words is "nine million, eight hundred eighty-one thousand, five hundred eighty-one".