81529805 has 16 divisors (see below), whose sum is σ = 112005504. Its totient is φ = 55809600.

The previous prime is 81529793. The next prime is 81529823. The reversal of 81529805 is 50892518.

It is not a de Polignac number, because 81529805 - 2¹⁰ = 81528781 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22874 + ... + 26196.

It is an arithmetic number, because the mean of its divisors is an integer number (7000344).

Almost surely, 2^81529805 is an apocalyptic number.

It is an amenable number.

81529805 is a deficient number, since it is larger than the sum of its proper divisors (30475699).

81529805 is a wasteful number, since it uses less digits than its factorization.

81529805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4036.

The product of its (nonzero) digits is 28800, while the sum is 38.

The square root of 81529805 is about 9029.3856380155. The cubic root of 81529805 is about 433.6161687399.

The spelling of 81529805 in words is "eighty-one million, five hundred twenty-nine thousand, eight hundred five".