81942239 has 2 divisors, whose sum is σ = 81942240. Its totient is φ = 81942238.

The previous prime is 81942229. The next prime is 81942251. The reversal of 81942239 is 93224918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81942239 - 2⁸ = 81941983 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 (81942229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40971119 + 40971120.

It is an arithmetic number, because the mean of its divisors is an integer number (40971120).

Almost surely, 2^81942239 is an apocalyptic number.

81942239 is a deficient number, since it is larger than the sum of its proper divisors (1).

81942239 is an equidigital number, since it uses as much as digits as its factorization.

81942239 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 38.

The square root of 81942239 is about 9052.1952586099. The cubic root of 81942239 is about 434.3461158372.

The spelling of 81942239 in words is "eighty-one million, nine hundred forty-two thousand, two hundred thirty-nine".