20001609 has 12 divisors (see below), whose sum is σ = 29157700. Its totient is φ = 13211424.

The previous prime is 20001557. The next prime is 20001613. The reversal of 20001609 is 90610002.

It can be written as a sum of positive squares in 2 ways, for example, as 17015625 + 2985984 = 4125^2 + 1728^2 .

It is not a de Polignac number, because 20001609 - 2²¹ = 17904457 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20001591 and 20001600.

It is not an unprimeable number, because it can be changed into a prime (20001659) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9214 + ... + 11175.

Almost surely, 2^20001609 is an apocalyptic number.

It is an amenable number.

20001609 is a deficient number, since it is larger than the sum of its proper divisors (9156091).

20001609 is a wasteful number, since it uses less digits than its factorization.

20001609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20504 (or 20501 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 20001609 is about 4472.3158430504. The cubic root of 20001609 is about 271.4490406275.

The spelling of 20001609 in words is "twenty million, one thousand, six hundred nine".