20805965 has 4 divisors (see below), whose sum is σ = 24967164. Its totient is φ = 16644768.

The previous prime is 20805959. The next prime is 20805989. The reversal of 20805965 is 56950802.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5541316 + 15264649 = 2354^2 + 3907^2 .

It is a cyclic number.

It is not a de Polignac number, because 20805965 - 2¹⁶ = 20740429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2080592 + ... + 2080601.

It is an arithmetic number, because the mean of its divisors is an integer number (6241791).

Almost surely, 2^20805965 is an apocalyptic number.

It is an amenable number.

20805965 is a deficient number, since it is larger than the sum of its proper divisors (4161199).

20805965 is an equidigital number, since it uses as much as digits as its factorization.

20805965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4161198.

The product of its (nonzero) digits is 21600, while the sum is 35.

The square root of 20805965 is about 4561.3556099037. The cubic root of 20805965 is about 275.0400602797.

The spelling of 20805965 in words is "twenty million, eight hundred five thousand, nine hundred sixty-five".