81680771 has 2 divisors, whose sum is σ = 81680772. Its totient is φ = 81680770.

The previous prime is 81680761. The next prime is 81680789. The reversal of 81680771 is 17708618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81680771 - 2²² = 77486467 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81680701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40840385 + 40840386.

It is an arithmetic number, because the mean of its divisors is an integer number (40840386).

Almost surely, 2^81680771 is an apocalyptic number.

81680771 is a deficient number, since it is larger than the sum of its proper divisors (1).

81680771 is an equidigital number, since it uses as much as digits as its factorization.

81680771 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18816, while the sum is 38.

The square root of 81680771 is about 9037.7414767186. The cubic root of 81680771 is about 433.8836412137.

The spelling of 81680771 in words is "eighty-one million, six hundred eighty thousand, seven hundred seventy-one".