99661566828121 has 2 divisors, whose sum is σ = 99661566828122. Its totient is φ = 99661566828120.

The previous prime is 99661566828017. The next prime is 99661566828139. The reversal of 99661566828121 is 12182866516699.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 99661566828096 + 25 = 9983064^2 + 5^2 .

It is an emirp because it is prime and its reverse (12182866516699) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 99661566828121 - 2²¹ = 99661564730969 is a prime.

It is not a weakly prime, because it can be changed into another prime (99661566823121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49830783414060 + 49830783414061.

It is an arithmetic number, because the mean of its divisors is an integer number (49830783414061).

Almost surely, 2^{99661566828121} is an apocalyptic number.

It is an amenable number.

99661566828121 is a deficient number, since it is larger than the sum of its proper divisors (1).

99661566828121 is an equidigital number, since it uses as much as digits as its factorization.

99661566828121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 134369280, while the sum is 70.

The spelling of 99661566828121 in words is "ninety-nine trillion, six hundred sixty-one billion, five hundred sixty-six million, eight hundred twenty-eight thousand, one hundred twenty-one".