81092821 has 2 divisors, whose sum is σ = 81092822. Its totient is φ = 81092820.

The previous prime is 81092819. The next prime is 81092833. The reversal of 81092821 is 12829018.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 79744900 + 1347921 = 8930^2 + 1161^2 .

It is a cyclic number.

It is not a de Polignac number, because 81092821 - 2¹ = 81092819 is a prime.

Together with 81092819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81092861) 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, 40546410 + 40546411.

It is an arithmetic number, because the mean of its divisors is an integer number (40546411).

Almost surely, 2^81092821 is an apocalyptic number.

It is an amenable number.

81092821 is a deficient number, since it is larger than the sum of its proper divisors (1).

81092821 is an equidigital number, since it uses as much as digits as its factorization.

81092821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 81092821 is about 9005.1552457467. The cubic root of 81092821 is about 432.8400808995.

The spelling of 81092821 in words is "eighty-one million, ninety-two thousand, eight hundred twenty-one".