81321632 has 24 divisors (see below), whose sum is σ = 182974176. Its totient is φ = 34852032.

The previous prime is 81321619. The next prime is 81321637. The reversal of 81321632 is 23612318.

It is a super-2 number, since 2×81321632² = 13226415662286848, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81321637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 181298 + ... + 181745.

It is an arithmetic number, because the mean of its divisors is an integer number (7623924).

Almost surely, 2^81321632 is an apocalyptic number.

It is an amenable number.

81321632 is an abundant number, since it is smaller than the sum of its proper divisors (101652544).

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

81321632 is a wasteful number, since it uses less digits than its factorization.

81321632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 363060 (or 363052 counting only the distinct ones).

The product of its digits is 1728, while the sum is 26.

The square root of 81321632 is about 9017.8507417233. The cubic root of 81321632 is about 433.2467982365.

The spelling of 81321632 in words is "eighty-one million, three hundred twenty-one thousand, six hundred thirty-two".