231321220181 has 2 divisors, whose sum is σ = 231321220182. Its totient is φ = 231321220180.

The previous prime is 231321220157. The next prime is 231321220187. The reversal of 231321220181 is 181022123132.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 180094140625 + 51227079556 = 424375^2 + 226334^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-231321220181 is a prime.

It is a super-2 number, since 2×231321220181² (a number of 24 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 231321220181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (231321220187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115660610090 + 115660610091.

It is an arithmetic number, because the mean of its divisors is an integer number (115660610091).

Almost surely, 2^231321220181 is an apocalyptic number.

It is an amenable number.

231321220181 is a deficient number, since it is larger than the sum of its proper divisors (1).

231321220181 is an equidigital number, since it uses as much as digits as its factorization.

231321220181 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 26.

The spelling of 231321220181 in words is "two hundred thirty-one billion, three hundred twenty-one million, two hundred twenty thousand, one hundred eighty-one".