1981331369 has 2 divisors, whose sum is σ = 1981331370. Its totient is φ = 1981331368.

The previous prime is 1981331357. The next prime is 1981331371. The reversal of 1981331369 is 9631331891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1981318144 + 13225 = 44512^2 + 115^2 .

It is a cyclic number.

It is not a de Polignac number, because 1981331369 - 2⁴ = 1981331353 is a prime.

It is a super-3 number, since 3×1981331369³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

Together with 1981331371, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1981331309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990665684 + 990665685.

It is an arithmetic number, because the mean of its divisors is an integer number (990665685).

Almost surely, 2^1981331369 is an apocalyptic number.

It is an amenable number.

1981331369 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981331369 is an equidigital number, since it uses as much as digits as its factorization.

1981331369 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 104976, while the sum is 44.

The square root of 1981331369 is about 44512.1485551978. The cubic root of 1981331369 is about 1255.9886220266.

The spelling of 1981331369 in words is "one billion, nine hundred eighty-one million, three hundred thirty-one thousand, three hundred sixty-nine".