166138578769 has 2 divisors, whose sum is σ = 166138578770. Its totient is φ = 166138578768.

The previous prime is 166138578743. The next prime is 166138578791. The reversal of 166138578769 is 967875831661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 166125532225 + 13046544 = 407585^2 + 3612^2 .

It is a cyclic number.

It is not a de Polignac number, because 166138578769 - 2²⁷ = 166004361041 is a prime.

It is a super-2 number, since 2×166138578769² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (166138579769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83069289384 + 83069289385.

It is an arithmetic number, because the mean of its divisors is an integer number (83069289385).

Almost surely, 2^166138578769 is an apocalyptic number.

It is an amenable number.

166138578769 is a deficient number, since it is larger than the sum of its proper divisors (1).

166138578769 is an equidigital number, since it uses as much as digits as its factorization.

166138578769 is an evil number, because the sum of its binary digits is even.

The product of its digits is 91445760, while the sum is 67.

The spelling of 166138578769 in words is "one hundred sixty-six billion, one hundred thirty-eight million, five hundred seventy-eight thousand, seven hundred sixty-nine".