9661581 has 6 divisors (see below), whose sum is σ = 13955630. Its totient is φ = 6441048.

The previous prime is 9661579. The next prime is 9661583. The reversal of 9661581 is 1851669.

9661581 is digitally balanced in base 2 and base 4, because in such bases 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 (9661579) and next prime (9661583).

It can be written as a sum of positive squares in only one way, i.e., 7209225 + 2452356 = 2685^2 + 1566^2 .

It is not a de Polignac number, because 9661581 - 2¹ = 9661579 is a prime.

It is a super-2 number, since 2×9661581² = 186692294839122, 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 (9661583) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 536746 + ... + 536763.

Almost surely, 2^9661581 is an apocalyptic number.

It is an amenable number.

9661581 is a deficient number, since it is larger than the sum of its proper divisors (4294049).

9661581 is a wasteful number, since it uses less digits than its factorization.

9661581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1073515 (or 1073512 counting only the distinct ones).

The product of its digits is 12960, while the sum is 36.

The square root of 9661581 is about 3108.3083823842. The cubic root of 9661581 is about 212.9851870939.

The spelling of 9661581 in words is "nine million, six hundred sixty-one thousand, five hundred eighty-one".