166761156509 has 2 divisors, whose sum is σ = 166761156510. Its totient is φ = 166761156508.

The previous prime is 166761156479. The next prime is 166761156517. The reversal of 166761156509 is 905651167661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 129366105625 + 37395050884 = 359675^2 + 193378^2 .

It is a cyclic number.

It is not a de Polignac number, because 166761156509 - 2¹⁶ = 166761090973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166761156539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83380578254 + 83380578255.

It is an arithmetic number, because the mean of its divisors is an integer number (83380578255).

Almost surely, 2^166761156509 is an apocalyptic number.

It is an amenable number.

166761156509 is a deficient number, since it is larger than the sum of its proper divisors (1).

166761156509 is an equidigital number, since it uses as much as digits as its factorization.

166761156509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2041200, while the sum is 53.

The spelling of 166761156509 in words is "one hundred sixty-six billion, seven hundred sixty-one million, one hundred fifty-six thousand, five hundred nine".