20919209 has 8 divisors (see below), whose sum is σ = 22350240. Its totient is φ = 19521216.

The previous prime is 20919191. The next prime is 20919211. The reversal of 20919209 is 90291902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20919209 - 2¹² = 20915113 is a prime.

It is a super-2 number, since 2×20919209² = 875226610371362, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20919229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6944 + ... + 9489.

It is an arithmetic number, because the mean of its divisors is an integer number (2793780).

Almost surely, 2^20919209 is an apocalyptic number.

It is an amenable number.

20919209 is a deficient number, since it is larger than the sum of its proper divisors (1431031).

20919209 is a wasteful number, since it uses less digits than its factorization.

20919209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16519.

The product of its (nonzero) digits is 2916, while the sum is 32.

The square root of 20919209 is about 4573.7521795567. The cubic root of 20919209 is about 275.5381593888.

The spelling of 20919209 in words is "twenty million, nine hundred nineteen thousand, two hundred nine".