20816825 has 6 divisors (see below), whose sum is σ = 25812894. Its totient is φ = 16653440.

The previous prime is 20816821. The next prime is 20816839. The reversal of 20816825 is 52861802.

It can be written as a sum of positive squares in 3 ways, for example, as 1430416 + 19386409 = 1196^2 + 4403^2 .

It is not a de Polignac number, because 20816825 - 2² = 20816821 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20816791 and 20816800.

It is not an unprimeable number, because it can be changed into a prime (20816821) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 416312 + ... + 416361.

It is an arithmetic number, because the mean of its divisors is an integer number (4302149).

Almost surely, 2^20816825 is an apocalyptic number.

20816825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20816825 is a deficient number, since it is larger than the sum of its proper divisors (4996069).

20816825 is an equidigital number, since it uses as much as digits as its factorization.

20816825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 832683 (or 832678 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 32.

The square root of 20816825 is about 4562.5458901802. The cubic root of 20816825 is about 275.0879057816.

The spelling of 20816825 in words is "twenty million, eight hundred sixteen thousand, eight hundred twenty-five".