16620809 has 4 divisors (see below), whose sum is σ = 16646916. Its totient is φ = 16594704.

The previous prime is 16620787. The next prime is 16620827. The reversal of 16620809 is 90802661.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5895184 + 10725625 = 2428^2 + 3275^2 .

It is a cyclic number.

It is not a de Polignac number, because 16620809 - 2⁸ = 16620553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16620899) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12074 + ... + 13379.

It is an arithmetic number, because the mean of its divisors is an integer number (4161729).

Almost surely, 2^16620809 is an apocalyptic number.

It is an amenable number.

16620809 is a deficient number, since it is larger than the sum of its proper divisors (26107).

16620809 is an equidigital number, since it uses as much as digits as its factorization.

16620809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26106.

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 16620809 is about 4076.8626417872. The cubic root of 16620809 is about 255.2019878531.

The spelling of 16620809 in words is "sixteen million, six hundred twenty thousand, eight hundred nine".