20831321 has 12 divisors (see below), whose sum is σ = 24825780. Its totient is φ = 17418240.

The previous prime is 20831299. The next prime is 20831323. The reversal of 20831321 is 12313802.

It can be written as a sum of positive squares in 2 ways, for example, as 1073296 + 19758025 = 1036^2 + 4445^2 .

It is not a de Polignac number, because 20831321 - 2¹⁸ = 20569177 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20831293 and 20831302.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20831323) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3176 + ... + 7193.

It is an arithmetic number, because the mean of its divisors is an integer number (2068815).

Almost surely, 2^20831321 is an apocalyptic number.

It is an amenable number.

20831321 is a deficient number, since it is larger than the sum of its proper divisors (3994459).

20831321 is a wasteful number, since it uses less digits than its factorization.

20831321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10424 (or 10417 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 20831321 is about 4564.1342004810. The cubic root of 20831321 is about 275.1517443516.

The spelling of 20831321 in words is "twenty million, eight hundred thirty-one thousand, three hundred twenty-one".