31220121312181 has 2 divisors, whose sum is σ = 31220121312182. Its totient is φ = 31220121312180.

The previous prime is 31220121312179. The next prime is 31220121312253. The reversal of 31220121312181 is 18121312102213.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25569355258225 + 5650766053956 = 5056615^2 + 2377134^2 .

It is a cyclic number.

It is not a de Polignac number, because 31220121312181 - 2¹ = 31220121312179 is a prime.

It is a super-2 number, since 2×31220121312181² (a number of 28 digits) contains 22 as substring.

Together with 31220121312179, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31220121310181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15610060656090 + 15610060656091.

It is an arithmetic number, because the mean of its divisors is an integer number (15610060656091).

Almost surely, 2^{31220121312181} is an apocalyptic number.

It is an amenable number.

31220121312181 is a deficient number, since it is larger than the sum of its proper divisors (1).

31220121312181 is an equidigital number, since it uses as much as digits as its factorization.

31220121312181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 28.

Adding to 31220121312181 its reverse (18121312102213), we get a palindrome (49341433414394).

The spelling of 31220121312181 in words is "thirty-one trillion, two hundred twenty billion, one hundred twenty-one million, three hundred twelve thousand, one hundred eighty-one".