20173209 has 16 divisors (see below), whose sum is σ = 30965760. Its totient is φ = 11442960.

The previous prime is 20173207. The next prime is 20173213. The reversal of 20173209 is 90237102.

It is not a de Polignac number, because 20173209 - 2¹ = 20173207 is a prime.

It is a super-2 number, since 2×20173209² = 813916722715362, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20173207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 537 + ... + 6374.

It is an arithmetic number, because the mean of its divisors is an integer number (1935360).

Almost surely, 2^20173209 is an apocalyptic number.

It is an amenable number.

20173209 is a deficient number, since it is larger than the sum of its proper divisors (10792551).

20173209 is a wasteful number, since it uses less digits than its factorization.

20173209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7060.

The product of its (nonzero) digits is 756, while the sum is 24.

The square root of 20173209 is about 4491.4595623249. The cubic root of 20173209 is about 272.2231129654.

The spelling of 20173209 in words is "twenty million, one hundred seventy-three thousand, two hundred nine".