20985559 has 8 divisors (see below), whose sum is σ = 24076800. Its totient is φ = 17917656.

The previous prime is 20985551. The next prime is 20985583. The reversal of 20985559 is 95558902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20985559 - 2³ = 20985551 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 (20985551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3859 + ... + 7540.

It is an arithmetic number, because the mean of its divisors is an integer number (3009600).

Almost surely, 2^20985559 is an apocalyptic number.

20985559 is a deficient number, since it is larger than the sum of its proper divisors (3091241).

20985559 is a wasteful number, since it uses less digits than its factorization.

20985559 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11669.

The product of its (nonzero) digits is 162000, while the sum is 43.

The square root of 20985559 is about 4580.9997817070. Note that the first 3 decimals coincide. The cubic root of 20985559 is about 275.8291624633.

The spelling of 20985559 in words is "twenty million, nine hundred eighty-five thousand, five hundred fifty-nine".