81961943033 has 2 divisors, whose sum is σ = 81961943034. Its totient is φ = 81961943032.

The previous prime is 81961942981. The next prime is 81961943069. The reversal of 81961943033 is 33034916918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 75428777449 + 6533165584 = 274643^2 + 80828^2 .

It is a cyclic number.

It is not a de Polignac number, because 81961943033 - 2¹⁰ = 81961942009 is a prime.

It is not a weakly prime, because it can be changed into another prime (81961943093) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40980971516 + 40980971517.

It is an arithmetic number, because the mean of its divisors is an integer number (40980971517).

Almost surely, 2^81961943033 is an apocalyptic number.

It is an amenable number.

81961943033 is a deficient number, since it is larger than the sum of its proper divisors (1).

81961943033 is an equidigital number, since it uses as much as digits as its factorization.

81961943033 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 419904, while the sum is 47.

The spelling of 81961943033 in words is "eighty-one billion, nine hundred sixty-one million, nine hundred forty-three thousand, thirty-three".