81695666 has 16 divisors (see below), whose sum is σ = 132668928. Its totient is φ = 37506000.

The previous prime is 81695651. The next prime is 81695683. The reversal of 81695666 is 66659618.

It is a self number, because there is not a number n which added to its sum of digits gives 81695666.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3260 + ... + 13191.

It is an arithmetic number, because the mean of its divisors is an integer number (8291808).

Almost surely, 2^81695666 is an apocalyptic number.

81695666 is a deficient number, since it is larger than the sum of its proper divisors (50973262).

81695666 is a wasteful number, since it uses less digits than its factorization.

81695666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16657.

The product of its digits is 466560, while the sum is 47.

The square root of 81695666 is about 9038.5654835267. The cubic root of 81695666 is about 433.9100134102.

The spelling of 81695666 in words is "eighty-one million, six hundred ninety-five thousand, six hundred sixty-six".