81529117 has 4 divisors (see below), whose sum is σ = 81655776. Its totient is φ = 81402460.

The previous prime is 81529103. The next prime is 81529141. The reversal of 81529117 is 71192518.

It is a happy number.

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: 71192518 = 2 ⋅35596259.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81529117 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81529517) 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, 62359 + ... + 63652.

It is an arithmetic number, because the mean of its divisors is an integer number (20413944).

Almost surely, 2^81529117 is an apocalyptic number.

It is an amenable number.

81529117 is a deficient number, since it is larger than the sum of its proper divisors (126659).

81529117 is a wasteful number, since it uses less digits than its factorization.

81529117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126658.

The product of its digits is 5040, while the sum is 34.

The square root of 81529117 is about 9029.3475401050. The cubic root of 81529117 is about 433.6149490274.

The spelling of 81529117 in words is "eighty-one million, five hundred twenty-nine thousand, one hundred seventeen".