81961043 has 2 divisors, whose sum is σ = 81961044. Its totient is φ = 81961042.

The previous prime is 81961027. The next prime is 81961081. The reversal of 81961043 is 34016918.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81961043 - 2⁴ = 81961027 is a prime.

It is a super-2 number, since 2×81961043² = 13435225139295698, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81961013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40980521 + 40980522.

It is an arithmetic number, because the mean of its divisors is an integer number (40980522).

Almost surely, 2^81961043 is an apocalyptic number.

81961043 is a deficient number, since it is larger than the sum of its proper divisors (1).

81961043 is an equidigital number, since it uses as much as digits as its factorization.

81961043 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 81961043 is about 9053.2338421141. The cubic root of 81961043 is about 434.3793376928.

The spelling of 81961043 in words is "eighty-one million, nine hundred sixty-one thousand, forty-three".