165867787768561 has 2 divisors, whose sum is σ = 165867787768562. Its totient is φ = 165867787768560.

The previous prime is 165867787768523. The next prime is 165867787768699.

165867787768561 is nontrivially palindromic in base 10.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 160918586666161 + 4949201102400 = 12685369^2 + 2224680^2 .

It is a palprime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165867787768561 is a prime.

It is not a weakly prime, because it can be changed into another prime (165867782768561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82933893884280 + 82933893884281.

It is an arithmetic number, because the mean of its divisors is an integer number (82933893884281).

Almost surely, 2^{165867787768561} is an apocalyptic number.

It is an amenable number.

165867787768561 is a deficient number, since it is larger than the sum of its proper divisors (1).

165867787768561 is an equidigital number, since it uses as much as digits as its factorization.

165867787768561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 39829708800, while the sum is 88.

The spelling of 165867787768561 in words is "one hundred sixty-five trillion, eight hundred sixty-seven billion, seven hundred eighty-seven million, seven hundred sixty-eight thousand, five hundred sixty-one".