20409559 has 4 divisors (see below), whose sum is σ = 20689216. Its totient is φ = 20129904.

The previous prime is 20409547. The next prime is 20409583. The reversal of 20409559 is 95590402.

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 20409559 - 2⁵ = 20409527 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20409539) 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, 139719 + ... + 139864.

It is an arithmetic number, because the mean of its divisors is an integer number (5172304).

Almost surely, 2^20409559 is an apocalyptic number.

20409559 is a deficient number, since it is larger than the sum of its proper divisors (279657).

20409559 is an equidigital number, since it uses as much as digits as its factorization.

20409559 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279656.

The product of its (nonzero) digits is 16200, while the sum is 34.

The square root of 20409559 is about 4517.6939914076. The cubic root of 20409559 is about 273.2821129815.

The spelling of 20409559 in words is "twenty million, four hundred nine thousand, five hundred fifty-nine".