9961866 has 20 divisors (see below), whose sum is σ = 22322322. Its totient is φ = 3320568.

The previous prime is 9961841. The next prime is 9961867. The reversal of 9961866 is 6681699.

Added to its reverse (6681699) it gives a triangular number (16643565 = T₅₇₆₉).

It can be written as a sum of positive squares in only one way, i.e., 5861241 + 4100625 = 2421^2 + 2025^2 .

It is not an unprimeable number, because it can be changed into a prime (9961867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 30585 + ... + 30908.

Almost surely, 2^9961866 is an apocalyptic number.

9961866 is an abundant number, since it is smaller than the sum of its proper divisors (12360456).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9961866 is a wasteful number, since it uses less digits than its factorization.

9961866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61507 (or 61498 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 9961866 is about 3156.2423861294. The cubic root of 9961866 is about 215.1692627797.

Adding to 9961866 its reverse (6681699), we get a triangular number (16643565 = T₅₇₆₉).

The spelling of 9961866 in words is "nine million, nine hundred sixty-one thousand, eight hundred sixty-six".