81405229 has 2 divisors, whose sum is σ = 81405230. Its totient is φ = 81405228.

The previous prime is 81405227. The next prime is 81405301. The reversal of 81405229 is 92250418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 44863204 + 36542025 = 6698^2 + 6045^2 .

It is a cyclic number.

It is not a de Polignac number, because 81405229 - 2¹ = 81405227 is a prime.

It is a super-2 number, since 2×81405229² = 13253622617084882, which contains 22 as substring.

Together with 81405227, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 81405229.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81405223) 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, 40702614 + 40702615.

It is an arithmetic number, because the mean of its divisors is an integer number (40702615).

Almost surely, 2^81405229 is an apocalyptic number.

It is an amenable number.

81405229 is a deficient number, since it is larger than the sum of its proper divisors (1).

81405229 is an equidigital number, since it uses as much as digits as its factorization.

81405229 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 81405229 is about 9022.4846356201. The cubic root of 81405229 is about 433.3952037234.

The spelling of 81405229 in words is "eighty-one million, four hundred five thousand, two hundred twenty-nine".