81606365 has 8 divisors (see below), whose sum is σ = 98181720. Its totient is φ = 65115712.

The previous prime is 81606361. The next prime is 81606373. The reversal of 81606365 is 56360618.

It can be written as a sum of positive squares in 4 ways, for example, as 3407716 + 78198649 = 1846^2 + 8843^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81606365 - 2² = 81606361 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81606361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19034 + ... + 22923.

It is an arithmetic number, because the mean of its divisors is an integer number (12272715).

Almost surely, 2^81606365 is an apocalyptic number.

It is an amenable number.

81606365 is a deficient number, since it is larger than the sum of its proper divisors (16575355).

81606365 is a wasteful number, since it uses less digits than its factorization.

81606365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42351.

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 81606365 is about 9033.6241343107. The cubic root of 81606365 is about 433.7518543662.

The spelling of 81606365 in words is "eighty-one million, six hundred six thousand, three hundred sixty-five".