81261835200 has 1008 divisors, whose sum is σ = 371226344160. Its totient is φ = 17139548160.

The previous prime is 81261835183. The next prime is 81261835211. The reversal of 81261835200 is 253816218.

It is a happy number.

81261835200 is a `hidden beast` number, since 8 + 1 + 2 + 618 + 35 + 2 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1008).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 27516924 + ... + 27519876.

Almost surely, 2^81261835200 is an apocalyptic number.

81261835200 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81261835200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (185613172080).

81261835200 is an abundant number, since it is smaller than the sum of its proper divisors (289964508960).

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

81261835200 is a wasteful number, since it uses less digits than its factorization.

81261835200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3011 (or 2983 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The spelling of 81261835200 in words is "eighty-one billion, two hundred sixty-one million, eight hundred thirty-five thousand, two hundred".