20731265 has 4 divisors (see below), whose sum is σ = 24877524. Its totient is φ = 16585008.

The previous prime is 20731253. The next prime is 20731267. The reversal of 20731265 is 56213702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8814961 + 11916304 = 2969^2 + 3452^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20731265 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20731267) 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, 2073122 + ... + 2073131.

It is an arithmetic number, because the mean of its divisors is an integer number (6219381).

Almost surely, 2^20731265 is an apocalyptic number.

It is an amenable number.

20731265 is a deficient number, since it is larger than the sum of its proper divisors (4146259).

20731265 is an equidigital number, since it uses as much as digits as its factorization.

20731265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4146258.

The product of its (nonzero) digits is 2520, while the sum is 26.

The square root of 20731265 is about 4553.1598917675. The cubic root of 20731265 is about 274.7105052708.

Adding to 20731265 its reverse (56213702), we get a palindrome (76944967).

The spelling of 20731265 in words is "twenty million, seven hundred thirty-one thousand, two hundred sixty-five".