81138049 has 2 divisors, whose sum is σ = 81138050. Its totient is φ = 81138048.

The previous prime is 81138023. The next prime is 81138073. The reversal of 81138049 is 94083118.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 68178049 + 12960000 = 8257^2 + 3600^2 .

It is a cyclic number.

It is not a de Polignac number, because 81138049 - 2¹⁷ = 81006977 is a prime.

It is not a weakly prime, because it can be changed into another prime (81138149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40569024 + 40569025.

It is an arithmetic number, because the mean of its divisors is an integer number (40569025).

Almost surely, 2^81138049 is an apocalyptic number.

It is an amenable number.

81138049 is a deficient number, since it is larger than the sum of its proper divisors (1).

81138049 is an equidigital number, since it uses as much as digits as its factorization.

81138049 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 81138049 is about 9007.6661239191. Note that the first 3 decimals coincide. The cubic root of 81138049 is about 432.9205354231.

The spelling of 81138049 in words is "eighty-one million, one hundred thirty-eight thousand, forty-nine".