81167666 has 4 divisors (see below), whose sum is σ = 121751502. Its totient is φ = 40583832.

The previous prime is 81167663. The next prime is 81167683. The reversal of 81167666 is 66676118.

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., 58079641 + 23088025 = 7621^2 + 4805^2 .

It is not an unprimeable number, because it can be changed into a prime (81167663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20291915 + ... + 20291918.

Almost surely, 2^81167666 is an apocalyptic number.

81167666 is a deficient number, since it is larger than the sum of its proper divisors (40583836).

81167666 is a wasteful number, since it uses less digits than its factorization.

81167666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40583835.

The product of its digits is 72576, while the sum is 41.

The square root of 81167666 is about 9009.3099624777. The cubic root of 81167666 is about 432.9732038809.

The spelling of 81167666 in words is "eighty-one million, one hundred sixty-seven thousand, six hundred sixty-six".