31001221 has 2 divisors, whose sum is σ = 31001222. Its totient is φ = 31001220.

The previous prime is 31001161. The next prime is 31001233. The reversal of 31001221 is 12210013.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17969121 + 13032100 = 4239^2 + 3610^2 .

It is a cyclic number.

It is not a de Polignac number, because 31001221 - 2⁷ = 31001093 is a prime.

It is a super-2 number, since 2×31001221² = 1922151406981682, which contains 22 as substring.

31001221 is a modest number, since divided by 1221 gives 31 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 31001198 and 31001207.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31001291) 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 as a sum of consecutive naturals, namely, 15500610 + 15500611.

It is an arithmetic number, because the mean of its divisors is an integer number (15500611).

Almost surely, 2^31001221 is an apocalyptic number.

It is an amenable number.

31001221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31001221 is an equidigital number, since it uses as much as digits as its factorization.

31001221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 31001221 is about 5567.8740107872. The cubic root of 31001221 is about 314.1421895138.

Adding to 31001221 its reverse (12210013), we get a palindrome (43211234).

The spelling of 31001221 in words is "thirty-one million, one thousand, two hundred twenty-one".