31671221 has 6 divisors (see below), whose sum is σ = 33644130. Its totient is φ = 29807936.

The previous prime is 31671217. The next prime is 31671247. The reversal of 31671221 is 12217613.

It can be written as a sum of positive squares in 3 ways, for example, as 4056196 + 27615025 = 2014^2 + 5255^2 .

It is not a de Polignac number, because 31671221 - 2² = 31671217 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31671281) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 54506 + ... + 55083.

It is an arithmetic number, because the mean of its divisors is an integer number (5607355).

Almost surely, 2^31671221 is an apocalyptic number.

It is an amenable number.

31671221 is a deficient number, since it is larger than the sum of its proper divisors (1972909).

31671221 is a wasteful number, since it uses less digits than its factorization.

31671221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109623 (or 109606 counting only the distinct ones).

The product of its digits is 504, while the sum is 23.

The square root of 31671221 is about 5627.7189872985. The cubic root of 31671221 is about 316.3891649544.

Adding to 31671221 its reverse (12217613), we get a palindrome (43888834).

The spelling of 31671221 in words is "thirty-one million, six hundred seventy-one thousand, two hundred twenty-one".