81666323 has 2 divisors, whose sum is σ = 81666324. Its totient is φ = 81666322.

The previous prime is 81666293. The next prime is 81666379. The reversal of 81666323 is 32366618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81666323 - 2¹² = 81662227 is a prime.

It is not a weakly prime, because it can be changed into another prime (81666023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40833161 + 40833162.

It is an arithmetic number, because the mean of its divisors is an integer number (40833162).

Almost surely, 2^81666323 is an apocalyptic number.

81666323 is a deficient number, since it is larger than the sum of its proper divisors (1).

81666323 is an equidigital number, since it uses as much as digits as its factorization.

81666323 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 35.

The square root of 81666323 is about 9036.9421266267. The cubic root of 81666323 is about 433.8580573852.

The spelling of 81666323 in words is "eighty-one million, six hundred sixty-six thousand, three hundred twenty-three".