20566439 has 4 divisors (see below), whose sum is σ = 21460656. Its totient is φ = 19672224.

The previous prime is 20566409. The next prime is 20566453. The reversal of 20566439 is 93466502.

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

It is a cyclic number.

It is not a de Polignac number, because 20566439 - 2²⁰ = 19517863 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20566399 and 20566408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20566409) 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, 447074 + ... + 447119.

It is an arithmetic number, because the mean of its divisors is an integer number (5365164).

Almost surely, 2^20566439 is an apocalyptic number.

20566439 is a deficient number, since it is larger than the sum of its proper divisors (894217).

20566439 is an equidigital number, since it uses as much as digits as its factorization.

20566439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 894216.

The product of its (nonzero) digits is 38880, while the sum is 35.

The square root of 20566439 is about 4535.0235942054. The cubic root of 20566439 is about 273.9805294563.

The spelling of 20566439 in words is "twenty million, five hundred sixty-six thousand, four hundred thirty-nine".