165407217509 has 2 divisors, whose sum is σ = 165407217510. Its totient is φ = 165407217508.

The previous prime is 165407217461. The next prime is 165407217533. The reversal of 165407217509 is 905712704561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 112658908609 + 52748308900 = 335647^2 + 229670^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165407217509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165407217709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82703608754 + 82703608755.

It is an arithmetic number, because the mean of its divisors is an integer number (82703608755).

Almost surely, 2^165407217509 is an apocalyptic number.

It is an amenable number.

165407217509 is a deficient number, since it is larger than the sum of its proper divisors (1).

165407217509 is an equidigital number, since it uses as much as digits as its factorization.

165407217509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 529200, while the sum is 47.

The spelling of 165407217509 in words is "one hundred sixty-five billion, four hundred seven million, two hundred seventeen thousand, five hundred nine".