81521175732 has 12 divisors (see below), whose sum is σ = 190216076736. Its totient is φ = 27173725240.

The previous prime is 81521175679. The next prime is 81521175739. The reversal of 81521175732 is 23757112518.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81521175739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3396715644 + ... + 3396715667.

It is an arithmetic number, because the mean of its divisors is an integer number (15851339728).

Almost surely, 2^81521175732 is an apocalyptic number.

It is an amenable number.

81521175732 is an abundant number, since it is smaller than the sum of its proper divisors (108694901004).

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

81521175732 is a wasteful number, since it uses less digits than its factorization.

81521175732 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6793431318 (or 6793431316 counting only the distinct ones).

The product of its digits is 117600, while the sum is 42.

The spelling of 81521175732 in words is "eighty-one billion, five hundred twenty-one million, one hundred seventy-five thousand, seven hundred thirty-two".