20731013 has 4 divisors (see below), whose sum is σ = 20742348. Its totient is φ = 20719680.

The previous prime is 20731001. The next prime is 20731043. The reversal of 20731013 is 31013702.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 15194404 + 5536609 = 3898^2 + 2353^2 .

It is a cyclic number.

It is not a de Polignac number, because 20731013 - 2⁸ = 20730757 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 = 20730982 and 20731000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20731043) 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 3 ways as a sum of consecutive naturals, for example, 2228 + ... + 6813.

It is an arithmetic number, because the mean of its divisors is an integer number (5185587).

Almost surely, 2^20731013 is an apocalyptic number.

It is an amenable number.

20731013 is a deficient number, since it is larger than the sum of its proper divisors (11335).

20731013 is an equidigital number, since it uses as much as digits as its factorization.

20731013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11334.

The product of its (nonzero) digits is 126, while the sum is 17.

The square root of 20731013 is about 4553.1322185941. The cubic root of 20731013 is about 274.7093921803.

Adding to 20731013 its reverse (31013702), we get a palindrome (51744715).

The spelling of 20731013 in words is "twenty million, seven hundred thirty-one thousand, thirteen".