81990143 has 2 divisors, whose sum is σ = 81990144. Its totient is φ = 81990142.

The previous prime is 81990107. The next prime is 81990151. The reversal of 81990143 is 34109918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81990143 - 2¹⁶ = 81924607 is a prime.

It is a Sophie Germain prime.

It is a plaindrome in base 12.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81990343) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40995071 + 40995072.

It is an arithmetic number, because the mean of its divisors is an integer number (40995072).

Almost surely, 2^81990143 is an apocalyptic number.

81990143 is a deficient number, since it is larger than the sum of its proper divisors (1).

81990143 is an equidigital number, since it uses as much as digits as its factorization.

81990143 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 81990143 is about 9054.8408600041. The cubic root of 81990143 is about 434.4307399305.

The spelling of 81990143 in words is "eighty-one million, nine hundred ninety thousand, one hundred forty-three".