20559989 has 4 divisors (see below), whose sum is σ = 20897100. Its totient is φ = 20222880.

The previous prime is 20559949. The next prime is 20559991. The reversal of 20559989 is 98995502.

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 3062500 + 17497489 = 1750^2 + 4183^2 .

It is a cyclic number.

It is not a de Polignac number, because 20559989 - 2⁸ = 20559733 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20559949) 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, 168464 + ... + 168585.

It is an arithmetic number, because the mean of its divisors is an integer number (5224275).

Almost surely, 2^20559989 is an apocalyptic number.

It is an amenable number.

20559989 is a deficient number, since it is larger than the sum of its proper divisors (337111).

20559989 is an equidigital number, since it uses as much as digits as its factorization.

20559989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 337110.

The product of its (nonzero) digits is 291600, while the sum is 47.

The square root of 20559989 is about 4534.3124065287. The cubic root of 20559989 is about 273.9518847440.

The spelling of 20559989 in words is "twenty million, five hundred fifty-nine thousand, nine hundred eighty-nine".