20995559 has 4 divisors (see below), whose sum is σ = 22610616. Its totient is φ = 19380504.

The previous prime is 20995547. The next prime is 20995571. The reversal of 20995559 is 95559902.

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

It is an interprime number because it is at equal distance from previous prime (20995547) and next prime (20995571).

It is not a de Polignac number, because 20995559 - 2¹² = 20991463 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 (20995859) 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, 807509 + ... + 807534.

It is an arithmetic number, because the mean of its divisors is an integer number (5652654).

Almost surely, 2^20995559 is an apocalyptic number.

20995559 is a deficient number, since it is larger than the sum of its proper divisors (1615057).

20995559 is a wasteful number, since it uses less digits than its factorization.

20995559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1615056.

The product of its (nonzero) digits is 182250, while the sum is 44.

The square root of 20995559 is about 4582.0911165100. The cubic root of 20995559 is about 275.8729680412.

The spelling of 20995559 in words is "twenty million, nine hundred ninety-five thousand, five hundred fifty-nine".