81321932160 has 384 divisors, whose sum is σ = 328765469760. Its totient is φ = 18134138880.

The previous prime is 81321932149. The next prime is 81321932171. The reversal of 81321932160 is 6123912318.

81321932160 is a `hidden beast` number, since 8 + 1 + 321 + 9 + 321 + 6 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (81321932149) and next prime (81321932171).

It is a tau number, because it is divible by the number of its divisors (384).

It is a super-2 number, since 2×81321932160² (a number of 23 digits) contains 22 as substring.

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 47 ways as a sum of consecutive naturals, for example, 1628524 + ... + 1677716.

Almost surely, 2^81321932160 is an apocalyptic number.

81321932160 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 81321932160, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (164382734880).

81321932160 is an abundant number, since it is smaller than the sum of its proper divisors (247443537600).

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

81321932160 is a wasteful number, since it uses less digits than its factorization.

81321932160 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49266 (or 49251 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The spelling of 81321932160 in words is "eighty-one billion, three hundred twenty-one million, nine hundred thirty-two thousand, one hundred sixty".