81433021 has 2 divisors, whose sum is σ = 81433022. Its totient is φ = 81433020.

The previous prime is 81433019. The next prime is 81433057. The reversal of 81433021 is 12033418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80192025 + 1240996 = 8955^2 + 1114^2 .

It is a cyclic number.

It is not a de Polignac number, because 81433021 - 2¹ = 81433019 is a prime.

Together with 81433019, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 81432983 and 81433001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81433081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40716510 + 40716511.

It is an arithmetic number, because the mean of its divisors is an integer number (40716511).

Almost surely, 2^81433021 is an apocalyptic number.

It is an amenable number.

81433021 is a deficient number, since it is larger than the sum of its proper divisors (1).

81433021 is an equidigital number, since it uses as much as digits as its factorization.

81433021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 81433021 is about 9024.0246564379. The cubic root of 81433021 is about 433.4445189381. Note that the first 3 decimals are identical.

Adding to 81433021 its reverse (12033418), we get a palindrome (93466439).

The spelling of 81433021 in words is "eighty-one million, four hundred thirty-three thousand, twenty-one".