81766879 has 4 divisors (see below), whose sum is σ = 82315800. Its totient is φ = 81217960.

The previous prime is 81766877. The next prime is 81766903. The reversal of 81766879 is 97866718.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 97866718 = 2 ⋅48933359.

It is a cyclic number.

It is not a de Polignac number, because 81766879 - 2¹ = 81766877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81766877) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 274237 + ... + 274534.

It is an arithmetic number, because the mean of its divisors is an integer number (20578950).

Almost surely, 2^81766879 is an apocalyptic number.

81766879 is a deficient number, since it is larger than the sum of its proper divisors (548921).

81766879 is a wasteful number, since it uses less digits than its factorization.

81766879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 548920.

The product of its digits is 1016064, while the sum is 52.

The square root of 81766879 is about 9042.5040226698. The cubic root of 81766879 is about 434.0360546119.

The spelling of 81766879 in words is "eighty-one million, seven hundred sixty-six thousand, eight hundred seventy-nine".