16509909 has 16 divisors (see below), whose sum is σ = 23853312. Its totient is φ = 10097088.

The previous prime is 16509901. The next prime is 16509919. The reversal of 16509909 is 90990561.

It is not a de Polignac number, because 16509909 - 2³ = 16509901 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16509901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5524 + ... + 7970.

It is an arithmetic number, because the mean of its divisors is an integer number (1490832).

Almost surely, 2^16509909 is an apocalyptic number.

It is an amenable number.

16509909 is a deficient number, since it is larger than the sum of its proper divisors (7343403).

16509909 is a wasteful number, since it uses less digits than its factorization.

16509909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2636.

The product of its (nonzero) digits is 21870, while the sum is 39.

The square root of 16509909 is about 4063.2387328337. The cubic root of 16509909 is about 254.6331210059.

The spelling of 16509909 in words is "sixteen million, five hundred nine thousand, nine hundred nine".