81993600 has 384 divisors, whose sum is σ = 327583200. Its totient is φ = 19906560.

The previous prime is 81993559. The next prime is 81993617. The reversal of 81993600 is 639918.

It is a tau number, because it is divible by the number of its divisors (384).

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 47 ways as a sum of consecutive naturals, for example, 1123164 + ... + 1123236.

Almost surely, 2^81993600 is an apocalyptic number.

81993600 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 81993600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (163791600).

81993600 is an abundant number, since it is smaller than the sum of its proper divisors (245589600).

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

81993600 is a wasteful number, since it uses less digits than its factorization.

81993600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119 (or 96 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

The square root of 81993600 is about 9055.0317503585. The cubic root of 81993600 is about 434.4368455667.

The spelling of 81993600 in words is "eighty-one million, nine hundred ninety-three thousand, six hundred".