9999944299661 has 2 divisors, whose sum is σ = 9999944299662. Its totient is φ = 9999944299660.

The previous prime is 9999944299607. The next prime is 9999944299673. The reversal of 9999944299661 is 1669924499999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9934820322025 + 65123977636 = 3151955^2 + 255194^2 .

It is a cyclic number.

It is not a de Polignac number, because 9999944299661 - 2³⁴ = 9982764430477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9999944295661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4999972149830 + 4999972149831.

It is an arithmetic number, because the mean of its divisors is an integer number (4999972149831).

Almost surely, 2^{9999944299661} is an apocalyptic number.

It is an amenable number.

9999944299661 is a deficient number, since it is larger than the sum of its proper divisors (1).

9999944299661 is an equidigital number, since it uses as much as digits as its factorization.

9999944299661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5509980288, while the sum is 86.

The spelling of 9999944299661 in words is "nine trillion, nine hundred ninety-nine billion, nine hundred forty-four million, two hundred ninety-nine thousand, six hundred sixty-one".