16689509 has 2 divisors, whose sum is σ = 16689510. Its totient is φ = 16689508.

The previous prime is 16689503. The next prime is 16689521. The reversal of 16689509 is 90598661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16564900 + 124609 = 4070^2 + 353^2 .

It is a cyclic number.

It is not a de Polignac number, because 16689509 - 2¹² = 16685413 is a prime.

It is a super-2 number, since 2×16689509² = 557079421322162, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a nialpdrome in base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 16689509.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16689503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8344754 + 8344755.

It is an arithmetic number, because the mean of its divisors is an integer number (8344755).

Almost surely, 2^16689509 is an apocalyptic number.

It is an amenable number.

16689509 is a deficient number, since it is larger than the sum of its proper divisors (1).

16689509 is an equidigital number, since it uses as much as digits as its factorization.

16689509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 116640, while the sum is 44.

The square root of 16689509 is about 4085.2795497983. The cubic root of 16689509 is about 255.5531194965.

The spelling of 16689509 in words is "sixteen million, six hundred eighty-nine thousand, five hundred nine".