661202161 has 2 divisors, whose sum is σ = 661202162. Its totient is φ = 661202160.

The previous prime is 661202159. The next prime is 661202177. The reversal of 661202161 is 161202166.

661202161 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 659462400 + 1739761 = 25680^2 + 1319^2 .

It is a cyclic number.

It is not a de Polignac number, because 661202161 - 2¹ = 661202159 is a prime.

It is a super-2 number, since 2×661202161² = 874376595422139842, which contains 22 as substring.

Together with 661202159, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (661202111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330601080 + 330601081.

It is an arithmetic number, because the mean of its divisors is an integer number (330601081).

Almost surely, 2^661202161 is an apocalyptic number.

It is an amenable number.

661202161 is a deficient number, since it is larger than the sum of its proper divisors (1).

661202161 is an equidigital number, since it uses as much as digits as its factorization.

661202161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 661202161 is about 25713.8515395885. The cubic root of 661202161 is about 871.1870707183.

The spelling of 661202161 in words is "six hundred sixty-one million, two hundred two thousand, one hundred sixty-one".