81739571 has 2 divisors, whose sum is σ = 81739572. Its totient is φ = 81739570.

The previous prime is 81739513. The next prime is 81739597. The reversal of 81739571 is 17593718.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81739571 - 2²² = 77545267 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 (81739271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40869785 + 40869786.

It is an arithmetic number, because the mean of its divisors is an integer number (40869786).

Almost surely, 2^81739571 is an apocalyptic number.

81739571 is a deficient number, since it is larger than the sum of its proper divisors (1).

81739571 is an equidigital number, since it uses as much as digits as its factorization.

81739571 is an evil number, because the sum of its binary digits is even.

The product of its digits is 52920, while the sum is 41.

The square root of 81739571 is about 9040.9939166001. The cubic root of 81739571 is about 433.9877303333.

The spelling of 81739571 in words is "eighty-one million, seven hundred thirty-nine thousand, five hundred seventy-one".