166487509 has 2 divisors, whose sum is σ = 166487510. Its totient is φ = 166487508.

The previous prime is 166487473. The next prime is 166487513. The reversal of 166487509 is 905784661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 166487409 + 100 = 12903^2 + 10^2 .

It is an emirp because it is prime and its reverse (905784661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 166487509 - 2⁷ = 166487381 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166487539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83243754 + 83243755.

It is an arithmetic number, because the mean of its divisors is an integer number (83243755).

Almost surely, 2^166487509 is an apocalyptic number.

It is an amenable number.

166487509 is a deficient number, since it is larger than the sum of its proper divisors (1).

166487509 is an equidigital number, since it uses as much as digits as its factorization.

166487509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 362880, while the sum is 46.

The square root of 166487509 is about 12903.0038750672. The cubic root of 166487509 is about 550.1239489241.

The spelling of 166487509 in words is "one hundred sixty-six million, four hundred eighty-seven thousand, five hundred nine".