166205261 has 2 divisors, whose sum is σ = 166205262. Its totient is φ = 166205260.

The previous prime is 166205251. The next prime is 166205287. The reversal of 166205261 is 162502661.

166205261 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., 163584100 + 2621161 = 12790^2 + 1619^2 .

It is an emirp because it is prime and its reverse (162502661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 166205261 - 2⁶ = 166205197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166205201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83102630 + 83102631.

It is an arithmetic number, because the mean of its divisors is an integer number (83102631).

Almost surely, 2^166205261 is an apocalyptic number.

It is an amenable number.

166205261 is a deficient number, since it is larger than the sum of its proper divisors (1).

166205261 is an equidigital number, since it uses as much as digits as its factorization.

166205261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 166205261 is about 12892.0619374870. The cubic root of 166205261 is about 549.8128961362.

The spelling of 166205261 in words is "one hundred sixty-six million, two hundred five thousand, two hundred sixty-one".