81866503310400 has 672 divisors, whose sum is σ = 303087872563200. Its totient is φ = 21491524454400.

The previous prime is 81866503310369. The next prime is 81866503310411. The reversal of 81866503310400 is 401330566818.

81866503310400 is a `hidden beast` number, since 8 + 18 + 66 + 503 + 31 + 0 + 40 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2094878061 + ... + 2094917139.

Almost surely, 2^{81866503310400} is an apocalyptic number.

81866503310400 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 81866503310400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (151543936281600).

81866503310400 is an abundant number, since it is smaller than the sum of its proper divisors (221221369252800).

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

81866503310400 is a wasteful number, since it uses less digits than its factorization.

81866503310400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39864 (or 39843 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 45.

The spelling of 81866503310400 in words is "eighty-one trillion, eight hundred sixty-six billion, five hundred three million, three hundred ten thousand, four hundred".