81716819 has 4 divisors (see below), whose sum is σ = 81737544. Its totient is φ = 81696096.

The previous prime is 81716749. The next prime is 81716827. The reversal of 81716819 is 91861718.

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 81716819 - 2¹² = 81712723 is a prime.

It is a super-2 number, since 2×81716819² = 13355277014957522, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (81716119) 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, 2417 + ... + 13010.

It is an arithmetic number, because the mean of its divisors is an integer number (20434386).

Almost surely, 2^81716819 is an apocalyptic number.

81716819 is a deficient number, since it is larger than the sum of its proper divisors (20725).

81716819 is a wasteful number, since it uses less digits than its factorization.

81716819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20724.

The product of its digits is 24192, while the sum is 41.

The square root of 81716819 is about 9039.7355602916. The cubic root of 81716819 is about 433.9474601394.

The spelling of 81716819 in words is "eighty-one million, seven hundred sixteen thousand, eight hundred nineteen".