81536129 has 4 divisors (see below), whose sum is σ = 82518576. Its totient is φ = 80553684.

The previous prime is 81536113. The next prime is 81536141. The reversal of 81536129 is 92163518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 92163518 = 2 ⋅46081759.

It is a cyclic number.

It is not a de Polignac number, because 81536129 - 2⁴ = 81536113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81536629) 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, 491099 + ... + 491264.

It is an arithmetic number, because the mean of its divisors is an integer number (20629644).

Almost surely, 2^81536129 is an apocalyptic number.

It is an amenable number.

81536129 is a deficient number, since it is larger than the sum of its proper divisors (982447).

81536129 is an equidigital number, since it uses as much as digits as its factorization.

81536129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 982446.

The product of its digits is 12960, while the sum is 35.

The square root of 81536129 is about 9029.7358211633. The cubic root of 81536129 is about 433.6273798455.

The spelling of 81536129 in words is "eighty-one million, five hundred thirty-six thousand, one hundred twenty-nine".