31440213221 has 2 divisors, whose sum is σ = 31440213222. Its totient is φ = 31440213220.

The previous prime is 31440213143. The next prime is 31440213223. The reversal of 31440213221 is 12231204413.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27352528996 + 4087684225 = 165386^2 + 63935^2 .

It is a cyclic number.

It is not a de Polignac number, because 31440213221 - 2¹⁰ = 31440212197 is a prime.

It is a super-3 number, since 3×31440213221³ (a number of 32 digits) contains 333 as substring.

Together with 31440213223, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31440213223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15720106610 + 15720106611.

It is an arithmetic number, because the mean of its divisors is an integer number (15720106611).

Almost surely, 2^31440213221 is an apocalyptic number.

It is an amenable number.

31440213221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31440213221 is an equidigital number, since it uses as much as digits as its factorization.

31440213221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1152, while the sum is 23.

Adding to 31440213221 its reverse (12231204413), we get a palindrome (43671417634).

The spelling of 31440213221 in words is "thirty-one billion, four hundred forty million, two hundred thirteen thousand, two hundred twenty-one".