31223021 has 2 divisors, whose sum is σ = 31223022. Its totient is φ = 31223020.

The previous prime is 31222991. The next prime is 31223041. The reversal of 31223021 is 12032213.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19758025 + 11464996 = 4445^2 + 3386^2 .

It is an emirp because it is prime and its reverse (12032213) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31223021 - 2⁶ = 31222957 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31222987 and 31223005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31223041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15611510 + 15611511.

It is an arithmetic number, because the mean of its divisors is an integer number (15611511).

Almost surely, 2^31223021 is an apocalyptic number.

It is an amenable number.

31223021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31223021 is an equidigital number, since it uses as much as digits as its factorization.

31223021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 31223021 is about 5587.7563475871. The cubic root of 31223021 is about 314.8895926161.

Adding to 31223021 its reverse (12032213), we get a palindrome (43255234).

The spelling of 31223021 in words is "thirty-one million, two hundred twenty-three thousand, twenty-one".