81865367519 has 16 divisors (see below), whose sum is σ = 89518772448. Its totient is φ = 74406701952.

The previous prime is 81865367513. The next prime is 81865367531. The reversal of 81865367519 is 91576356818.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81865367519 is a prime.

It is a super-2 number, since 2×81865367519² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81865367513) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2033009 + ... + 2072885.

It is an arithmetic number, because the mean of its divisors is an integer number (5594923278).

Almost surely, 2^81865367519 is an apocalyptic number.

81865367519 is a deficient number, since it is larger than the sum of its proper divisors (7653404929).

81865367519 is a wasteful number, since it uses less digits than its factorization.

81865367519 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42314.

The product of its digits is 10886400, while the sum is 59.

The spelling of 81865367519 in words is "eighty-one billion, eight hundred sixty-five million, three hundred sixty-seven thousand, five hundred nineteen".