81659674 has 4 divisors (see below), whose sum is σ = 122489514. Its totient is φ = 40829836.

The previous prime is 81659671. The next prime is 81659689. The reversal of 81659674 is 47695618.

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

It can be written as a sum of positive squares in only one way, i.e., 43652449 + 38007225 = 6607^2 + 6165^2 .

It is not an unprimeable number, because it can be changed into a prime (81659671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20414917 + ... + 20414920.

Almost surely, 2^81659674 is an apocalyptic number.

81659674 is a deficient number, since it is larger than the sum of its proper divisors (40829840).

81659674 is a wasteful number, since it uses less digits than its factorization.

81659674 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40829839.

The product of its digits is 362880, while the sum is 46.

The square root of 81659674 is about 9036.5742402749. The cubic root of 81659674 is about 433.8462826397.

The spelling of 81659674 in words is "eighty-one million, six hundred fifty-nine thousand, six hundred seventy-four".