81360599040 has 864 divisors, whose sum is σ = 336576371040. Its totient is φ = 18489212928.

The previous prime is 81360599039. The next prime is 81360599051. The reversal of 81360599040 is 4099506318.

It is a happy number.

81360599040 is a `hidden beast` number, since 8 + 13 + 6 + 0 + 599 + 0 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (864).

It is a super-2 number, since 2×81360599040² (a number of 23 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 470292394 + ... + 470292566.

It is an arithmetic number, because the mean of its divisors is an integer number (389555985).

Almost surely, 2^81360599040 is an apocalyptic number.

81360599040 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 81360599040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (168288185520).

81360599040 is an abundant number, since it is smaller than the sum of its proper divisors (255215772000).

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

81360599040 is an frugal number, since it uses more digits than its factorization.

81360599040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 231 (or 190 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 45.

The spelling of 81360599040 in words is "eighty-one billion, three hundred sixty million, five hundred ninety-nine thousand, forty".