20816447 has 4 divisors (see below), whose sum is σ = 20932920. Its totient is φ = 20699976.

The previous prime is 20816437. The next prime is 20816489. The reversal of 20816447 is 74461802.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20816447 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 (20816437) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 57968 + ... + 58325.

It is an arithmetic number, because the mean of its divisors is an integer number (5233230).

Almost surely, 2^20816447 is an apocalyptic number.

20816447 is a deficient number, since it is larger than the sum of its proper divisors (116473).

20816447 is a wasteful number, since it uses less digits than its factorization.

20816447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116472.

The product of its (nonzero) digits is 10752, while the sum is 32.

The square root of 20816447 is about 4562.5044657512. The cubic root of 20816447 is about 275.0862407205.

The spelling of 20816447 in words is "twenty million, eight hundred sixteen thousand, four hundred forty-seven".