81056791 has 4 divisors (see below), whose sum is σ = 82167232. Its totient is φ = 79946352.

The previous prime is 81056783. The next prime is 81056797. The reversal of 81056791 is 19765018.

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 81056791 - 2³ = 81056783 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81056791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81056797) 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 in 3 ways as a sum of consecutive naturals, for example, 555111 + ... + 555256.

It is an arithmetic number, because the mean of its divisors is an integer number (20541808).

Almost surely, 2^81056791 is an apocalyptic number.

81056791 is a deficient number, since it is larger than the sum of its proper divisors (1110441).

81056791 is a wasteful number, since it uses less digits than its factorization.

81056791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1110440.

The product of its (nonzero) digits is 15120, while the sum is 37.

The square root of 81056791 is about 9003.1545027285. The cubic root of 81056791 is about 432.7759669694.

The spelling of 81056791 in words is "eighty-one million, fifty-six thousand, seven hundred ninety-one".