331806781 has 2 divisors, whose sum is σ = 331806782. Its totient is φ = 331806780.

The previous prime is 331806773. The next prime is 331806803. The reversal of 331806781 is 187608133.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 285103225 + 46703556 = 16885^2 + 6834^2 .

It is an emirp because it is prime and its reverse (187608133) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 331806781 - 2³ = 331806773 is a prime.

It is a super-2 number, since 2×331806781² = 220191479835163922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 331806781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (331806701) 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, 165903390 + 165903391.

It is an arithmetic number, because the mean of its divisors is an integer number (165903391).

Almost surely, 2^331806781 is an apocalyptic number.

It is an amenable number.

331806781 is a deficient number, since it is larger than the sum of its proper divisors (1).

331806781 is an equidigital number, since it uses as much as digits as its factorization.

331806781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 331806781 is about 18215.5642514856. The cubic root of 331806781 is about 692.3012021731.

The spelling of 331806781 in words is "three hundred thirty-one million, eight hundred six thousand, seven hundred eighty-one".