81768971 has 4 divisors (see below), whose sum is σ = 82135872. Its totient is φ = 81402072.

The previous prime is 81768961. The next prime is 81768977. The reversal of 81768971 is 17986718.

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

It is a cyclic number.

It is not a de Polignac number, because 81768971 - 2¹⁰ = 81767947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81768977) 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, 183116 + ... + 183561.

It is an arithmetic number, because the mean of its divisors is an integer number (20533968).

Almost surely, 2^81768971 is an apocalyptic number.

81768971 is a deficient number, since it is larger than the sum of its proper divisors (366901).

81768971 is a wasteful number, since it uses less digits than its factorization.

81768971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 366900.

The product of its digits is 169344, while the sum is 47.

The square root of 81768971 is about 9042.6196978531. The cubic root of 81768971 is about 434.0397561746.

The spelling of 81768971 in words is "eighty-one million, seven hundred sixty-eight thousand, nine hundred seventy-one".