20309684 has 6 divisors (see below), whose sum is σ = 35541954. Its totient is φ = 10154840.

The previous prime is 20309683. The next prime is 20309699. The reversal of 20309684 is 48690302.

It can be written as a sum of positive squares in only one way, i.e., 12802084 + 7507600 = 3578^2 + 2740^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 20309684.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20309683) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2538707 + ... + 2538714.

It is an arithmetic number, because the mean of its divisors is an integer number (5923659).

Almost surely, 2^20309684 is an apocalyptic number.

It is an amenable number.

20309684 is a deficient number, since it is larger than the sum of its proper divisors (15232270).

20309684 is a wasteful number, since it uses less digits than its factorization.

20309684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5077425 (or 5077423 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 20309684 is about 4506.6266763512. The cubic root of 20309684 is about 272.8356115165.

Adding to 20309684 its reverse (48690302), we get a palindrome (68999986).

The spelling of 20309684 in words is "twenty million, three hundred nine thousand, six hundred eighty-four".