166815639111409 has 2 divisors, whose sum is σ = 166815639111410. Its totient is φ = 166815639111408.

The previous prime is 166815639111389. The next prime is 166815639111437. The reversal of 166815639111409 is 904111936518661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 165754681430625 + 1060957680784 = 12874575^2 + 1030028^2 .

It is a cyclic number.

It is not a de Polignac number, because 166815639111409 - 2⁵ = 166815639111377 is a prime.

It is a super-2 number, since 2×166815639111409² (a number of 29 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (166815639111449) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83407819555704 + 83407819555705.

It is an arithmetic number, because the mean of its divisors is an integer number (83407819555705).

Almost surely, 2^{166815639111409} is an apocalyptic number.

It is an amenable number.

166815639111409 is a deficient number, since it is larger than the sum of its proper divisors (1).

166815639111409 is an equidigital number, since it uses as much as digits as its factorization.

166815639111409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8398080, while the sum is 61.

The spelling of 166815639111409 in words is "one hundred sixty-six trillion, eight hundred fifteen billion, six hundred thirty-nine million, one hundred eleven thousand, four hundred nine".