81386539 has 4 divisors (see below), whose sum is σ = 87647056. Its totient is φ = 75126024.

The previous prime is 81386533. The next prime is 81386549. The reversal of 81386539 is 93568318.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93568318 = 2 ⋅46784159.

It is a cyclic number.

It is not a de Polignac number, because 81386539 - 2⁹ = 81386027 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81386495 and 81386504.

It is not an unprimeable number, because it can be changed into a prime (81386533) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3130239 + ... + 3130264.

It is an arithmetic number, because the mean of its divisors is an integer number (21911764).

Almost surely, 2^81386539 is an apocalyptic number.

81386539 is a deficient number, since it is larger than the sum of its proper divisors (6260517).

81386539 is a wasteful number, since it uses less digits than its factorization.

81386539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6260516.

The product of its digits is 155520, while the sum is 43.

The square root of 81386539 is about 9021.4488304263. The cubic root of 81386539 is about 433.3620331419.

The spelling of 81386539 in words is "eighty-one million, three hundred eighty-six thousand, five hundred thirty-nine".