81654239 has 2 divisors, whose sum is σ = 81654240. Its totient is φ = 81654238.

The previous prime is 81654233. The next prime is 81654259. The reversal of 81654239 is 93245618.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81654239 - 2²⁰ = 80605663 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81654233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40827119 + 40827120.

It is an arithmetic number, because the mean of its divisors is an integer number (40827120).

Almost surely, 2^81654239 is an apocalyptic number.

81654239 is a deficient number, since it is larger than the sum of its proper divisors (1).

81654239 is an equidigital number, since it uses as much as digits as its factorization.

81654239 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 38.

The square root of 81654239 is about 9036.2735129034. The cubic root of 81654239 is about 433.8366572977.

It can be divided in two parts, 816 and 54239, that added together give a palindrome (55055).

The spelling of 81654239 in words is "eighty-one million, six hundred fifty-four thousand, two hundred thirty-nine".