16542509 has 2 divisors, whose sum is σ = 16542510. Its totient is φ = 16542508.

The previous prime is 16542473. The next prime is 16542511. The reversal of 16542509 is 90524561.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16176484 + 366025 = 4022^2 + 605^2 .

It is an emirp because it is prime and its reverse (90524561) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16542509 is a prime.

Together with 16542511, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16542569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8271254 + 8271255.

It is an arithmetic number, because the mean of its divisors is an integer number (8271255).

Almost surely, 2^16542509 is an apocalyptic number.

It is an amenable number.

16542509 is a deficient number, since it is larger than the sum of its proper divisors (1).

16542509 is an equidigital number, since it uses as much as digits as its factorization.

16542509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10800, while the sum is 32.

The square root of 16542509 is about 4067.2483327183. The cubic root of 16542509 is about 254.8006079389.

The spelling of 16542509 in words is "sixteen million, five hundred forty-two thousand, five hundred nine".