31283221 has 4 divisors (see below), whose sum is σ = 31322700. Its totient is φ = 31243744.

The previous prime is 31283191. The next prime is 31283227. The reversal of 31283221 is 12238213.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16112196 + 15171025 = 4014^2 + 3895^2 .

It is a cyclic number.

It is not a de Polignac number, because 31283221 - 2¹³ = 31275029 is a prime.

It is a super-2 number, since 2×31283221² = 1957279832269682, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31283192 and 31283201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31283227) 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 3 ways as a sum of consecutive naturals, for example, 18526 + ... + 20143.

It is an arithmetic number, because the mean of its divisors is an integer number (7830675).

Almost surely, 2^31283221 is an apocalyptic number.

It is an amenable number.

31283221 is a deficient number, since it is larger than the sum of its proper divisors (39479).

31283221 is an equidigital number, since it uses as much as digits as its factorization.

31283221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39478.

The product of its digits is 576, while the sum is 22.

The square root of 31283221 is about 5593.1405310434. The cubic root of 31283221 is about 315.0918385111.

The spelling of 31283221 in words is "thirty-one million, two hundred eighty-three thousand, two hundred twenty-one".