81401839 has 2 divisors, whose sum is σ = 81401840. Its totient is φ = 81401838.

The previous prime is 81401819. The next prime is 81401891. The reversal of 81401839 is 93810418.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81401839 - 2¹³ = 81393647 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81401809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40700919 + 40700920.

It is an arithmetic number, because the mean of its divisors is an integer number (40700920).

Almost surely, 2^81401839 is an apocalyptic number.

81401839 is a deficient number, since it is larger than the sum of its proper divisors (1).

81401839 is an equidigital number, since it uses as much as digits as its factorization.

81401839 is an odious number, because the sum of its binary digits is odd.

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

The square root of 81401839 is about 9022.2967696701. The cubic root of 81401839 is about 433.3891876064.

The spelling of 81401839 in words is "eighty-one million, four hundred one thousand, eight hundred thirty-nine".