81305771 has 2 divisors, whose sum is σ = 81305772. Its totient is φ = 81305770.

The previous prime is 81305767. The next prime is 81305789. The reversal of 81305771 is 17750318.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81305771 - 2² = 81305767 is a prime.

It is a super-2 number, since 2×81305771² = 13221256795808882, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81305701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40652885 + 40652886.

It is an arithmetic number, because the mean of its divisors is an integer number (40652886).

Almost surely, 2^81305771 is an apocalyptic number.

81305771 is a deficient number, since it is larger than the sum of its proper divisors (1).

81305771 is an equidigital number, since it uses as much as digits as its factorization.

81305771 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5880, while the sum is 32.

The square root of 81305771 is about 9016.9712764320. The cubic root of 81305771 is about 433.2186295353.

The spelling of 81305771 in words is "eighty-one million, three hundred five thousand, seven hundred seventy-one".