81816079 has 2 divisors, whose sum is σ = 81816080. Its totient is φ = 81816078.

The previous prime is 81816061. The next prime is 81816089. The reversal of 81816079 is 97061818.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81816079 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81816089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40908039 + 40908040.

It is an arithmetic number, because the mean of its divisors is an integer number (40908040).

Almost surely, 2^81816079 is an apocalyptic number.

81816079 is a deficient number, since it is larger than the sum of its proper divisors (1).

81816079 is an equidigital number, since it uses as much as digits as its factorization.

81816079 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 40.

The square root of 81816079 is about 9045.2240989375. The cubic root of 81816079 is about 434.1230918593.

The spelling of 81816079 in words is "eighty-one million, eight hundred sixteen thousand, seventy-nine".