20406321 has 12 divisors (see below), whose sum is σ = 31743348. Its totient is φ = 12557664.

The previous prime is 20406311. The next prime is 20406329. The reversal of 20406321 is 12360402.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 11189025 + 9217296 = 3345^2 + 3036^2 .

It is not a de Polignac number, because 20406321 - 2⁵ = 20406289 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20406294 and 20406303.

It is not an unprimeable number, because it can be changed into a prime (20406329) 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 11 ways as a sum of consecutive naturals, for example, 87090 + ... + 87323.

It is an arithmetic number, because the mean of its divisors is an integer number (2645279).

Almost surely, 2^20406321 is an apocalyptic number.

It is an amenable number.

20406321 is a deficient number, since it is larger than the sum of its proper divisors (11337027).

20406321 is a wasteful number, since it uses less digits than its factorization.

20406321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174432 (or 174429 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 20406321 is about 4517.3356085197. The cubic root of 20406321 is about 273.2676600433.

Adding to 20406321 its reverse (12360402), we get a palindrome (32766723).

The spelling of 20406321 in words is "twenty million, four hundred six thousand, three hundred twenty-one".