321131981 has 2 divisors, whose sum is σ = 321131982. Its totient is φ = 321131980.

The previous prime is 321131971. The next prime is 321132013. The reversal of 321131981 is 189131123.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 174504100 + 146627881 = 13210^2 + 12109^2 .

It is an emirp because it is prime and its reverse (189131123) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 321131981 - 2¹⁸ = 320869837 is a prime.

It is a super-2 number, since 2×321131981² = 206251498441968722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (321131971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160565990 + 160565991.

It is an arithmetic number, because the mean of its divisors is an integer number (160565991).

Almost surely, 2^321131981 is an apocalyptic number.

It is an amenable number.

321131981 is a deficient number, since it is larger than the sum of its proper divisors (1).

321131981 is an equidigital number, since it uses as much as digits as its factorization.

321131981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296, while the sum is 29.

The square root of 321131981 is about 17920.1557191895. The cubic root of 321131981 is about 684.7959546412.

The spelling of 321131981 in words is "three hundred twenty-one million, one hundred thirty-one thousand, nine hundred eighty-one".