331161781 has 2 divisors, whose sum is σ = 331161782. Its totient is φ = 331161780.

The previous prime is 331161739. The next prime is 331161829. The reversal of 331161781 is 187161133.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 215943025 + 115218756 = 14695^2 + 10734^2 .

It is a cyclic number.

It is not a de Polignac number, because 331161781 - 2¹¹ = 331159733 is a prime.

It is a super-2 number, since 2×331161781² = 219336250390183922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (331161731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165580890 + 165580891.

It is an arithmetic number, because the mean of its divisors is an integer number (165580891).

Almost surely, 2^331161781 is an apocalyptic number.

It is an amenable number.

331161781 is a deficient number, since it is larger than the sum of its proper divisors (1).

331161781 is an equidigital number, since it uses as much as digits as its factorization.

331161781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 31.

The square root of 331161781 is about 18197.8509994999. The cubic root of 331161781 is about 691.8523225303.

The spelling of 331161781 in words is "three hundred thirty-one million, one hundred sixty-one thousand, seven hundred eighty-one".