81533621030400 has 4320 divisors, whose sum is σ = 397080825343488. Its totient is φ = 15757236633600.

The previous prime is 81533621030399. The next prime is 81533621030431. The reversal of 81533621030400 is 403012633518.

81533621030400 is a `hidden beast` number, since 8 + 1 + 5 + 3 + 3 + 6 + 210 + 30 + 400 = 666.

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 pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 431 ways as a sum of consecutive naturals, for example, 52840972029 + ... + 52840973571.

Almost surely, 2^{81533621030400} is an apocalyptic number.

81533621030400 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 81533621030400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (198540412671744).

81533621030400 is an abundant number, since it is smaller than the sum of its proper divisors (315547204313088).

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

81533621030400 is a wasteful number, since it uses less digits than its factorization.

81533621030400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1662 (or 1631 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

Adding to 81533621030400 its reverse (403012633518), we get a palindrome (81936633663918).

The spelling of 81533621030400 in words is "eighty-one trillion, five hundred thirty-three billion, six hundred twenty-one million, thirty thousand, four hundred".