81812799619 has 4 divisors (see below), whose sum is σ = 82622827440. Its totient is φ = 81002771800.

The previous prime is 81812799611. The next prime is 81812799631. The reversal of 81812799619 is 91699721818.

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 81812799619 - 2³ = 81812799611 is a prime.

It is a super-2 number, since 2×81812799619² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81812799611) 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, 405013759 + ... + 405013960.

It is an arithmetic number, because the mean of its divisors is an integer number (20655706860).

Almost surely, 2^81812799619 is an apocalyptic number.

81812799619 is a deficient number, since it is larger than the sum of its proper divisors (810027821).

81812799619 is a wasteful number, since it uses less digits than its factorization.

81812799619 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 810027820.

The product of its digits is 3919104, while the sum is 61.

The spelling of 81812799619 in words is "eighty-one billion, eight hundred twelve million, seven hundred ninety-nine thousand, six hundred nineteen".