166776775261 has 2 divisors, whose sum is σ = 166776775262. Its totient is φ = 166776775260.

The previous prime is 166776775219. The next prime is 166776775271. The reversal of 166776775261 is 162577677661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 85398372900 + 81378402361 = 292230^2 + 285269^2 .

It is a cyclic number.

It is not a de Polignac number, because 166776775261 - 2¹¹ = 166776773213 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 166776775261.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166776775271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83388387630 + 83388387631.

It is an arithmetic number, because the mean of its divisors is an integer number (83388387631).

Almost surely, 2^166776775261 is an apocalyptic number.

It is an amenable number.

166776775261 is a deficient number, since it is larger than the sum of its proper divisors (1).

166776775261 is an equidigital number, since it uses as much as digits as its factorization.

166776775261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31116960, while the sum is 61.

The spelling of 166776775261 in words is "one hundred sixty-six billion, seven hundred seventy-six million, seven hundred seventy-five thousand, two hundred sixty-one".