1666723672169 has 2 divisors, whose sum is σ = 1666723672170. Its totient is φ = 1666723672168.

The previous prime is 1666723672123. The next prime is 1666723672193. The reversal of 1666723672169 is 9612763276661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1658737926400 + 7985745769 = 1287920^2 + 89363^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666723672169 - 2²⁸ = 1666455236713 is a prime.

It is a super-2 number, since 2×1666723672169² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1666723672109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833361836084 + 833361836085.

It is an arithmetic number, because the mean of its divisors is an integer number (833361836085).

Almost surely, 2^{1666723672169} is an apocalyptic number.

It is an amenable number.

1666723672169 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666723672169 is an equidigital number, since it uses as much as digits as its factorization.

1666723672169 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41150592, while the sum is 62.

The spelling of 1666723672169 in words is "one trillion, six hundred sixty-six billion, seven hundred twenty-three million, six hundred seventy-two thousand, one hundred sixty-nine".