20646047 has 4 divisors (see below), whose sum is σ = 20996040. Its totient is φ = 20296056.

The previous prime is 20646029. The next prime is 20646049. The reversal of 20646047 is 74064602.

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

It is a cyclic number.

It is not a de Polignac number, because 20646047 - 2⁸ = 20645791 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20646049) 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 3 ways as a sum of consecutive naturals, for example, 174908 + ... + 175025.

It is an arithmetic number, because the mean of its divisors is an integer number (5249010).

Almost surely, 2^20646047 is an apocalyptic number.

20646047 is a deficient number, since it is larger than the sum of its proper divisors (349993).

20646047 is an equidigital number, since it uses as much as digits as its factorization.

20646047 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 349992.

The product of its (nonzero) digits is 8064, while the sum is 29.

The square root of 20646047 is about 4543.7921387317. The cubic root of 20646047 is about 274.3335797258. Note that the first 3 decimals are identical.

The spelling of 20646047 in words is "twenty million, six hundred forty-six thousand, forty-seven".