31001231221 has 2 divisors, whose sum is σ = 31001231222. Its totient is φ = 31001231220.

The previous prime is 31001231207. The next prime is 31001231243. The reversal of 31001231221 is 12213210013.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27678976900 + 3322254321 = 166370^2 + 57639^2 .

It is a cyclic number.

It is not a de Polignac number, because 31001231221 - 2¹¹ = 31001229173 is a prime.

It is a super-2 number, since 2×31001231221² (a number of 22 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 31001231195 and 31001231204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31001231291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15500615610 + 15500615611.

It is an arithmetic number, because the mean of its divisors is an integer number (15500615611).

Almost surely, 2^31001231221 is an apocalyptic number.

It is an amenable number.

31001231221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31001231221 is an equidigital number, since it uses as much as digits as its factorization.

31001231221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 31001231221 its reverse (12213210013), we get a palindrome (43214441234).

It can be divided in two parts, 3100 and 1231221, that added together give a palindrome (1234321).

The spelling of 31001231221 in words is "thirty-one billion, one million, two hundred thirty-one thousand, two hundred twenty-one".