20641709 has 4 divisors (see below), whose sum is σ = 22518240. Its totient is φ = 18765180.

The previous prime is 20641679. The next prime is 20641717. The reversal of 20641709 is 90714602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20641709 - 2¹² = 20637613 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20641739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 938249 + ... + 938270.

It is an arithmetic number, because the mean of its divisors is an integer number (5629560).

Almost surely, 2^20641709 is an apocalyptic number.

It is an amenable number.

20641709 is a deficient number, since it is larger than the sum of its proper divisors (1876531).

20641709 is a wasteful number, since it uses less digits than its factorization.

20641709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1876530.

The product of its (nonzero) digits is 3024, while the sum is 29.

The square root of 20641709 is about 4543.3147590718. The cubic root of 20641709 is about 274.3143647088.

It can be divided in two parts, 2064 and 1709, that added together give a palindrome (3773).

The spelling of 20641709 in words is "twenty million, six hundred forty-one thousand, seven hundred nine".