81993029 has 2 divisors, whose sum is σ = 81993030. Its totient is φ = 81993028.

The previous prime is 81993017. The next prime is 81993049. The reversal of 81993029 is 92039918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81993025 + 4 = 9055^2 + 2^2 .

It is a cyclic number.

It is not a de Polignac number, because 81993029 - 2¹⁶ = 81927493 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81993049) 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, 40996514 + 40996515.

It is an arithmetic number, because the mean of its divisors is an integer number (40996515).

Almost surely, 2^81993029 is an apocalyptic number.

It is an amenable number.

81993029 is a deficient number, since it is larger than the sum of its proper divisors (1).

81993029 is an equidigital number, since it uses as much as digits as its factorization.

81993029 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 34992, while the sum is 41.

The square root of 81993029 is about 9055.0002208724. Note that the first 3 decimals coincide. The cubic root of 81993029 is about 434.4358370977.

The spelling of 81993029 in words is "eighty-one million, nine hundred ninety-three thousand, twenty-nine".