20812705 has 8 divisors (see below), whose sum is σ = 25135272. Its totient is φ = 16543488.

The previous prime is 20812703. The next prime is 20812717. The reversal of 20812705 is 50721802.

It can be written as a sum of positive squares in 4 ways, for example, as 28224 + 20784481 = 168^2 + 4559^2 .

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 20812705 - 2¹ = 20812703 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20812705.

It is not an unprimeable number, because it can be changed into a prime (20812703) 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, 12472 + ... + 14041.

It is an arithmetic number, because the mean of its divisors is an integer number (3141909).

Almost surely, 2^20812705 is an apocalyptic number.

It is an amenable number.

20812705 is a deficient number, since it is larger than the sum of its proper divisors (4322567).

20812705 is a wasteful number, since it uses less digits than its factorization.

20812705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26675.

The product of its (nonzero) digits is 1120, while the sum is 25.

The square root of 20812705 is about 4562.0943655299. The cubic root of 20812705 is about 275.0697564088.

The spelling of 20812705 in words is "twenty million, eight hundred twelve thousand, seven hundred five".