81755539 has 2 divisors, whose sum is σ = 81755540. Its totient is φ = 81755538.

The previous prime is 81755503. The next prime is 81755543. The reversal of 81755539 is 93555718.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81755539 - 2¹¹ = 81753491 is a prime.

It is equal to p_4765984 and since 81755539 and 4765984 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 81755495 and 81755504.

It is not a weakly prime, because it can be changed into another prime (81755579) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40877769 + 40877770.

It is an arithmetic number, because the mean of its divisors is an integer number (40877770).

Almost surely, 2^81755539 is an apocalyptic number.

81755539 is a deficient number, since it is larger than the sum of its proper divisors (1).

81755539 is an equidigital number, since it uses as much as digits as its factorization.

81755539 is an evil number, because the sum of its binary digits is even.

The product of its digits is 189000, while the sum is 43.

The square root of 81755539 is about 9041.8769622242. The cubic root of 81755539 is about 434.0159886370.

The spelling of 81755539 in words is "eighty-one million, seven hundred fifty-five thousand, five hundred thirty-nine".