81716563 has 4 divisors (see below), whose sum is σ = 81736200. Its totient is φ = 81696928.

The previous prime is 81716477. The next prime is 81716581. The reversal of 81716563 is 36561718.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81716563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81716363) 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, 838 + ... + 12811.

It is an arithmetic number, because the mean of its divisors is an integer number (20434050).

Almost surely, 2^81716563 is an apocalyptic number.

81716563 is a deficient number, since it is larger than the sum of its proper divisors (19637).

81716563 is a wasteful number, since it uses less digits than its factorization.

81716563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19636.

The product of its digits is 30240, while the sum is 37.

The square root of 81716563 is about 9039.7214005742. The cubic root of 81716563 is about 433.9470069864.

The spelling of 81716563 in words is "eighty-one million, seven hundred sixteen thousand, five hundred sixty-three".