661194161 has 2 divisors, whose sum is σ = 661194162. Its totient is φ = 661194160.

The previous prime is 661194137. The next prime is 661194203. The reversal of 661194161 is 161491166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 596873761 + 64320400 = 24431^2 + 8020^2 .

It is a cyclic number.

It is not a de Polignac number, because 661194161 - 2⁶ = 661194097 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (661191161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330597080 + 330597081.

It is an arithmetic number, because the mean of its divisors is an integer number (330597081).

Almost surely, 2^661194161 is an apocalyptic number.

It is an amenable number.

661194161 is a deficient number, since it is larger than the sum of its proper divisors (1).

661194161 is an equidigital number, since it uses as much as digits as its factorization.

661194161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7776, while the sum is 35.

The square root of 661194161 is about 25713.6959809359. The cubic root of 661194161 is about 871.1835571561.

The spelling of 661194161 in words is "six hundred sixty-one million, one hundred ninety-four thousand, one hundred sixty-one".