81732520321 has 27 divisors (see below), whose sum is σ = 88490883747. Its totient is φ = 75474696000.

The previous prime is 81732520283. The next prime is 81732520327. The reversal of 81732520321 is 12302523718.

The square root of 81732520321 is 285889.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 63632585025 + 18099935296 = 252255^2 + 134536^2 .

It is not a de Polignac number, because 81732520321 - 2²¹ = 81730423169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81732520327) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 325627446 + ... + 325627696.

Almost surely, 2^81732520321 is an apocalyptic number.

81732520321 is the 285889-th square number.

81732520321 is the 142945-th centered octagonal number.

It is an amenable number.

81732520321 is a deficient number, since it is larger than the sum of its proper divisors (6758363426).

81732520321 is an frugal number, since it uses more digits than its factorization.

81732520321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 670 (or 335 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 34.

The spelling of 81732520321 in words is "eighty-one billion, seven hundred thirty-two million, five hundred twenty thousand, three hundred twenty-one".