81661735 has 4 divisors (see below), whose sum is σ = 97994088. Its totient is φ = 65329384.

The previous prime is 81661733. The next prime is 81661739. The reversal of 81661735 is 53716618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 53716618 = 2 ⋅26858309.

It is a cyclic number.

It is not a de Polignac number, because 81661735 - 2¹ = 81661733 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81661694 and 81661703.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81661733) 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, 8166169 + ... + 8166178.

It is an arithmetic number, because the mean of its divisors is an integer number (24498522).

Almost surely, 2^81661735 is an apocalyptic number.

81661735 is a deficient number, since it is larger than the sum of its proper divisors (16332353).

81661735 is a wasteful number, since it uses less digits than its factorization.

81661735 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16332352.

The product of its digits is 30240, while the sum is 37.

The square root of 81661735 is about 9036.6882761330. The cubic root of 81661735 is about 433.8499325427.

The spelling of 81661735 in words is "eighty-one million, six hundred sixty-one thousand, seven hundred thirty-five".