20731285 has 8 divisors (see below), whose sum is σ = 25550136. Its totient is φ = 16136640.

The previous prime is 20731283. The next prime is 20731301. The reversal of 20731285 is 58213702.

It can be written as a sum of positive squares in 4 ways, for example, as 10504081 + 10227204 = 3241^2 + 3198^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20731285 - 2¹ = 20731283 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20731283) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 55846 + ... + 56215.

It is an arithmetic number, because the mean of its divisors is an integer number (3193767).

Almost surely, 2^20731285 is an apocalyptic number.

It is an amenable number.

20731285 is a deficient number, since it is larger than the sum of its proper divisors (4818851).

20731285 is a wasteful number, since it uses less digits than its factorization.

20731285 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112103.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 20731285 is about 4553.1620880439. The cubic root of 20731285 is about 274.7105936110.

Adding to 20731285 its reverse (58213702), we get a palindrome (78944987).

The spelling of 20731285 in words is "twenty million, seven hundred thirty-one thousand, two hundred eighty-five".