9961561 has 4 divisors (see below), whose sum is σ = 9970852. Its totient is φ = 9952272.

The previous prime is 9961543. The next prime is 9961573. The reversal of 9961561 is 1651699.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 7617600 + 2343961 = 2760^2 + 1531^2 .

It is a cyclic number.

It is not a de Polignac number, because 9961561 - 2¹¹ = 9959513 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 9961561.

It is not an unprimeable number, because it can be changed into a prime (9961531) 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 3 ways as a sum of consecutive naturals, for example, 2790 + ... + 5263.

It is an arithmetic number, because the mean of its divisors is an integer number (2492713).

Almost surely, 2^9961561 is an apocalyptic number.

It is an amenable number.

9961561 is a deficient number, since it is larger than the sum of its proper divisors (9291).

9961561 is a wasteful number, since it uses less digits than its factorization.

9961561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9290.

The product of its digits is 14580, while the sum is 37.

The square root of 9961561 is about 3156.1940688114. The cubic root of 9961561 is about 215.1670668291.

The spelling of 9961561 in words is "nine million, nine hundred sixty-one thousand, five hundred sixty-one".