20566865 has 8 divisors (see below), whose sum is σ = 26923968. Its totient is φ = 14957680.

The previous prime is 20566841. The next prime is 20566867. The reversal of 20566865 is 56866502.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20566865 - 2¹⁶ = 20501329 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20566867) 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, 186917 + ... + 187026.

It is an arithmetic number, because the mean of its divisors is an integer number (3365496).

Almost surely, 2^20566865 is an apocalyptic number.

It is an amenable number.

20566865 is a deficient number, since it is larger than the sum of its proper divisors (6357103).

20566865 is a wasteful number, since it uses less digits than its factorization.

20566865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 373959.

The product of its (nonzero) digits is 86400, while the sum is 38.

The square root of 20566865 is about 4535.0705617443. The cubic root of 20566865 is about 273.9824211288.

The spelling of 20566865 in words is "twenty million, five hundred sixty-six thousand, eight hundred sixty-five".