3261561661 has 8 divisors (see below), whose sum is σ = 3275444664. Its totient is φ = 3247695360.

The previous prime is 3261561629. The next prime is 3261561697. The reversal of 3261561661 is 1661651623.

It can be written as a sum of positive squares in 4 ways, for example, as 44970436 + 3216591225 = 6706^2 + 56715^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 3261561661 - 2⁵ = 3261561629 is a prime.

It is a super-4 number, since 4×3261561661⁴ (a number of 39 digits) contains 4444 as substring.

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 3261561661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3261561361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 523215 + ... + 529411.

It is an arithmetic number, because the mean of its divisors is an integer number (409430583).

Almost surely, 2^3261561661 is an apocalyptic number.

It is an amenable number.

3261561661 is a deficient number, since it is larger than the sum of its proper divisors (13883003).

3261561661 is a wasteful number, since it uses less digits than its factorization.

3261561661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8351.

The product of its digits is 38880, while the sum is 37.

The square root of 3261561661 is about 57110.0837068201. The cubic root of 3261561661 is about 1483.0024362379.

The spelling of 3261561661 in words is "three billion, two hundred sixty-one million, five hundred sixty-one thousand, six hundred sixty-one".