661823038081 has 2 divisors, whose sum is σ = 661823038082. Its totient is φ = 661823038080.

The previous prime is 661823038057. The next prime is 661823038171. The reversal of 661823038081 is 180830328166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 520477116481 + 141345921600 = 721441^2 + 375960^2 .

It is a cyclic number.

It is not a de Polignac number, because 661823038081 - 2²⁹ = 661286167169 is a prime.

It is a super-2 number, since 2×661823038081² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (661823038021) 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, 330911519040 + 330911519041.

It is an arithmetic number, because the mean of its divisors is an integer number (330911519041).

Almost surely, 2^661823038081 is an apocalyptic number.

It is an amenable number.

661823038081 is a deficient number, since it is larger than the sum of its proper divisors (1).

661823038081 is an equidigital number, since it uses as much as digits as its factorization.

661823038081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 331776, while the sum is 46.

The spelling of 661823038081 in words is "six hundred sixty-one billion, eight hundred twenty-three million, thirty-eight thousand, eighty-one".