20984809 has 8 divisors (see below), whose sum is σ = 22489920. Its totient is φ = 19529136.

The previous prime is 20984801. The next prime is 20984819. The reversal of 20984809 is 90848902.

It is a happy number.

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 20984809 - 2³ = 20984801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20984801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11479 + ... + 13180.

It is an arithmetic number, because the mean of its divisors is an integer number (2811240).

Almost surely, 2^20984809 is an apocalyptic number.

It is an amenable number.

20984809 is a deficient number, since it is larger than the sum of its proper divisors (1505111).

20984809 is a wasteful number, since it uses less digits than its factorization.

20984809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24719.

The product of its (nonzero) digits is 41472, while the sum is 40.

The square root of 20984809 is about 4580.9179211158. The cubic root of 20984809 is about 275.8258764841.

The spelling of 20984809 in words is "twenty million, nine hundred eighty-four thousand, eight hundred nine".