81581347 has 2 divisors, whose sum is σ = 81581348. Its totient is φ = 81581346.

The previous prime is 81581333. The next prime is 81581389. The reversal of 81581347 is 74318518.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81581347 is a prime.

It is not a weakly prime, because it can be changed into another prime (81551347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40790673 + 40790674.

It is an arithmetic number, because the mean of its divisors is an integer number (40790674).

Almost surely, 2^81581347 is an apocalyptic number.

81581347 is a deficient number, since it is larger than the sum of its proper divisors (1).

81581347 is an equidigital number, since it uses as much as digits as its factorization.

81581347 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26880, while the sum is 37.

The square root of 81581347 is about 9032.2393125957. The cubic root of 81581347 is about 433.7075248460.

The spelling of 81581347 in words is "eighty-one million, five hundred eighty-one thousand, three hundred forty-seven".