1321731881 has 2 divisors, whose sum is σ = 1321731882. Its totient is φ = 1321731880.

The previous prime is 1321731863. The next prime is 1321731889. The reversal of 1321731881 is 1881371231.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 722265625 + 599466256 = 26875^2 + 24484^2 .

It is a cyclic number.

It is not a de Polignac number, because 1321731881 - 2¹⁴ = 1321715497 is a prime.

It is a super-2 number, since 2×1321731881² = 3493950330503596322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1321731889) 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, 660865940 + 660865941.

It is an arithmetic number, because the mean of its divisors is an integer number (660865941).

Almost surely, 2^1321731881 is an apocalyptic number.

It is an amenable number.

1321731881 is a deficient number, since it is larger than the sum of its proper divisors (1).

1321731881 is an equidigital number, since it uses as much as digits as its factorization.

1321731881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 35.

The square root of 1321731881 is about 36355.6306643139. The cubic root of 1321731881 is about 1097.4408499280.

The spelling of 1321731881 in words is "one billion, three hundred twenty-one million, seven hundred thirty-one thousand, eight hundred eighty-one".