20661589 has 8 divisors (see below), whose sum is σ = 22315832. Its totient is φ = 19016640.

The previous prime is 20661587. The next prime is 20661631. The reversal of 20661589 is 98516602.

It can be written as a sum of positive squares in 4 ways, for example, as 5098564 + 15563025 = 2258^2 + 3945^2 .

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 20661589 - 2¹ = 20661587 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 (20661583) 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 7 ways as a sum of consecutive naturals, for example, 2719 + ... + 6979.

It is an arithmetic number, because the mean of its divisors is an integer number (2789479).

Almost surely, 2^20661589 is an apocalyptic number.

It is an amenable number.

20661589 is a deficient number, since it is larger than the sum of its proper divisors (1654243).

20661589 is a wasteful number, since it uses less digits than its factorization.

20661589 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4647.

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 20661589 is about 4545.5020624789. The cubic root of 20661589 is about 274.4024003748.

It can be divided in two parts, 2066 and 1589, that added together give a triangular number (3655 = T₈₅).

The spelling of 20661589 in words is "twenty million, six hundred sixty-one thousand, five hundred eighty-nine".