20505659 has 4 divisors (see below), whose sum is σ = 21059904. Its totient is φ = 19951416.

The previous prime is 20505643. The next prime is 20505679. The reversal of 20505659 is 95650502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 95650502 = 2 ⋅47825251.

It is a cyclic number.

It is not a de Polignac number, because 20505659 - 2⁴ = 20505643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20505619) 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 3 ways as a sum of consecutive naturals, for example, 277067 + ... + 277140.

It is an arithmetic number, because the mean of its divisors is an integer number (5264976).

Almost surely, 2^20505659 is an apocalyptic number.

20505659 is a deficient number, since it is larger than the sum of its proper divisors (554245).

20505659 is an equidigital number, since it uses as much as digits as its factorization.

20505659 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 554244.

The product of its (nonzero) digits is 13500, while the sum is 32.

The square root of 20505659 is about 4528.3174579528. The cubic root of 20505659 is about 273.7103649101.

The spelling of 20505659 in words is "twenty million, five hundred five thousand, six hundred fifty-nine".