81358517 has 2 divisors, whose sum is σ = 81358518. Its totient is φ = 81358516.

The previous prime is 81358493. The next prime is 81358561. The reversal of 81358517 is 71585318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 63457156 + 17901361 = 7966^2 + 4231^2 .

It is a cyclic number.

It is not a de Polignac number, because 81358517 - 2¹⁴ = 81342133 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81358117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40679258 + 40679259.

It is an arithmetic number, because the mean of its divisors is an integer number (40679259).

Almost surely, 2^81358517 is an apocalyptic number.

It is an amenable number.

81358517 is a deficient number, since it is larger than the sum of its proper divisors (1).

81358517 is an equidigital number, since it uses as much as digits as its factorization.

81358517 is an evil number, because the sum of its binary digits is even.

The product of its digits is 33600, while the sum is 38.

The square root of 81358517 is about 9019.8956202386. The cubic root of 81358517 is about 433.3122908257.

The spelling of 81358517 in words is "eighty-one million, three hundred fifty-eight thousand, five hundred seventeen".