31706221 has 4 divisors (see below), whose sum is σ = 31718844. Its totient is φ = 31693600.

The previous prime is 31706219. The next prime is 31706261. The reversal of 31706221 is 12260713.

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 8328996 + 23377225 = 2886^2 + 4835^2 .

It is a cyclic number.

It is not a de Polignac number, because 31706221 - 2¹ = 31706219 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31706192 and 31706201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31706261) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1120 + ... + 8041.

It is an arithmetic number, because the mean of its divisors is an integer number (7929711).

Almost surely, 2^31706221 is an apocalyptic number.

It is an amenable number.

31706221 is a deficient number, since it is larger than the sum of its proper divisors (12623).

31706221 is an equidigital number, since it uses as much as digits as its factorization.

31706221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12622.

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 31706221 is about 5630.8277366654. The cubic root of 31706221 is about 316.5056697155.

Adding to 31706221 its reverse (12260713), we get a palindrome (43966934).

The spelling of 31706221 in words is "thirty-one million, seven hundred six thousand, two hundred twenty-one".