81663600 has 60 divisors (see below), whose sum is σ = 261599576. Its totient is φ = 21776640.

The previous prime is 81663599. The next prime is 81663607. The reversal of 81663600 is 636618.

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

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81663607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32827 + ... + 35226.

Almost surely, 2^81663600 is an apocalyptic number.

81663600 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81663600 is an abundant number, since it is smaller than the sum of its proper divisors (179935976).

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

81663600 is a wasteful number, since it uses less digits than its factorization.

81663600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68074 (or 68063 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 81663600 is about 9036.7914660016. The cubic root of 81663600 is about 433.8532352889.

The spelling of 81663600 in words is "eighty-one million, six hundred sixty-three thousand, six hundred".