81522605 has 4 divisors (see below), whose sum is σ = 97827132. Its totient is φ = 65218080.

The previous prime is 81522569. The next prime is 81522613. The reversal of 81522605 is 50622518.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19333609 + 62188996 = 4397^2 + 7886^2 .

It is not a de Polignac number, because 81522605 - 2⁸ = 81522349 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8152256 + ... + 8152265.

It is an arithmetic number, because the mean of its divisors is an integer number (24456783).

Almost surely, 2^81522605 is an apocalyptic number.

It is an amenable number.

81522605 is a deficient number, since it is larger than the sum of its proper divisors (16304527).

81522605 is a wasteful number, since it uses less digits than its factorization.

81522605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16304526.

The product of its (nonzero) digits is 4800, while the sum is 29.

The square root of 81522605 is about 9028.9869309907. The cubic root of 81522605 is about 433.6034039671.

The spelling of 81522605 in words is "eighty-one million, five hundred twenty-two thousand, six hundred five".