81779171 has 2 divisors, whose sum is σ = 81779172. Its totient is φ = 81779170.

The previous prime is 81779167. The next prime is 81779189. The reversal of 81779171 is 17197718.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81779171 - 2² = 81779167 is a prime.

It is a plaindrome in base 12.

It is not a weakly prime, because it can be changed into another prime (81779111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40889585 + 40889586.

It is an arithmetic number, because the mean of its divisors is an integer number (40889586).

Almost surely, 2^81779171 is an apocalyptic number.

81779171 is a deficient number, since it is larger than the sum of its proper divisors (1).

81779171 is an equidigital number, since it uses as much as digits as its factorization.

81779171 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24696, while the sum is 41.

The square root of 81779171 is about 9043.1836761176. The cubic root of 81779171 is about 434.0578030424.

The spelling of 81779171 in words is "eighty-one million, seven hundred seventy-nine thousand, one hundred seventy-one".