81517604800 has 42 divisors (see below), whose sum is σ = 200584260248. Its totient is φ = 32607041280.

The previous prime is 81517604713. The next prime is 81517604869. The reversal of 81517604800 is 840671518.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 25472652 + ... + 25475851.

Almost surely, 2^81517604800 is an apocalyptic number.

81517604800 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81517604800 is an abundant number, since it is smaller than the sum of its proper divisors (119066655448).

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

81517604800 is a wasteful number, since it uses less digits than its factorization.

81517604800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50948525 (or 50948510 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 40.

The spelling of 81517604800 in words is "eighty-one billion, five hundred seventeen million, six hundred four thousand, eight hundred".