9661999229081 has 2 divisors, whose sum is σ = 9661999229082. Its totient is φ = 9661999229080.

The previous prime is 9661999229033. The next prime is 9661999229087. The reversal of 9661999229081 is 1809229991669.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5435500565056 + 4226498664025 = 2331416^2 + 2055845^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9661999229081 is a prime.

It is a super-2 number, since 2×9661999229081² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 9661999228996 and 9661999229014.

It is not a weakly prime, because it can be changed into another prime (9661999229087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4830999614540 + 4830999614541.

It is an arithmetic number, because the mean of its divisors is an integer number (4830999614541).

Almost surely, 2^{9661999229081} is an apocalyptic number.

It is an amenable number.

9661999229081 is a deficient number, since it is larger than the sum of its proper divisors (1).

9661999229081 is an equidigital number, since it uses as much as digits as its factorization.

9661999229081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 68024448, while the sum is 71.

The spelling of 9661999229081 in words is "nine trillion, six hundred sixty-one billion, nine hundred ninety-nine million, two hundred twenty-nine thousand, eighty-one".