20847209 has 8 divisors (see below), whose sum is σ = 21127392. Its totient is φ = 20569120.

The previous prime is 20847191. The next prime is 20847227. The reversal of 20847209 is 90274802.

It is an interprime number because it is at equal distance from previous prime (20847191) and next prime (20847227).

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 20847209 - 2⁸ = 20846953 is a prime.

It is a super-2 number, since 2×20847209² = 869212246179362, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20847289) 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 7 ways as a sum of consecutive naturals, for example, 30182 + ... + 30864.

It is an arithmetic number, because the mean of its divisors is an integer number (2640924).

Almost surely, 2^20847209 is an apocalyptic number.

It is an amenable number.

20847209 is a deficient number, since it is larger than the sum of its proper divisors (280183).

20847209 is a wasteful number, since it uses less digits than its factorization.

20847209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1047.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 20847209 is about 4565.8743959947. The cubic root of 20847209 is about 275.2216791064.

The spelling of 20847209 in words is "twenty million, eight hundred forty-seven thousand, two hundred nine".