81535534800 has 60 divisors (see below), whose sum is σ = 261185500320. Its totient is φ = 21742808960.

The previous prime is 81535534777. The next prime is 81535534837. The reversal of 81535534800 is 843553518.

It is a tau number, because it is divible by the number of its divisors (60).

It is a super-2 number, since 2×81535534800² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 33971940 + ... + 33974339.

It is an arithmetic number, because the mean of its divisors is an integer number (4353091672).

Almost surely, 2^81535534800 is an apocalyptic number.

81535534800 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81535534800 is an abundant number, since it is smaller than the sum of its proper divisors (179649965520).

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

81535534800 is a wasteful number, since it uses less digits than its factorization.

81535534800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67946300 (or 67946289 counting only the distinct ones).

The product of its (nonzero) digits is 288000, while the sum is 42.

The spelling of 81535534800 in words is "eighty-one billion, five hundred thirty-five million, five hundred thirty-four thousand, eight hundred".