81865367520 has 96 divisors (see below), whose sum is σ = 257915417760. Its totient is φ = 21827420160.

The previous prime is 81865367513. The next prime is 81865367531. The reversal of 81865367520 is 2576356818.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6084000 + ... + 6097440.

It is an arithmetic number, because the mean of its divisors is an integer number (2686618935).

Almost surely, 2^81865367520 is an apocalyptic number.

81865367520 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81865367520 is an abundant number, since it is smaller than the sum of its proper divisors (176050050240).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81865367520 is a wasteful number, since it uses less digits than its factorization.

81865367520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26148 (or 26140 counting only the distinct ones).

The product of its (nonzero) digits is 2419200, while the sum is 51.

The spelling of 81865367520 in words is "eighty-one billion, eight hundred sixty-five million, three hundred sixty-seven thousand, five hundred twenty".