81660379 has 2 divisors, whose sum is σ = 81660380. Its totient is φ = 81660378.

The previous prime is 81660377. The next prime is 81660389. The reversal of 81660379 is 97306618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81660379 - 2¹ = 81660377 is a prime.

Together with 81660377, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (81660377) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40830189 + 40830190.

It is an arithmetic number, because the mean of its divisors is an integer number (40830190).

Almost surely, 2^81660379 is an apocalyptic number.

81660379 is a deficient number, since it is larger than the sum of its proper divisors (1).

81660379 is an equidigital number, since it uses as much as digits as its factorization.

81660379 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54432, while the sum is 40.

The square root of 81660379 is about 9036.6132483359. The cubic root of 81660379 is about 433.8475311578.

The spelling of 81660379 in words is "eighty-one million, six hundred sixty thousand, three hundred seventy-nine".