521123728321 has 27 divisors (see below), whose sum is σ = 610032345507. Its totient is φ = 443875108320.

The previous prime is 521123728283. The next prime is 521123728351. The reversal of 521123728321 is 123827321125.

The square root of 521123728321 is 721889.

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., 352169846721 + 168953881600 = 593439^2 + 411040^2 .

It is not a de Polignac number, because 521123728321 - 2¹⁹ = 521123204033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (521123728351) 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 26 ways as a sum of consecutive naturals, for example, 1419955480 + ... + 1419955846.

Almost surely, 2^521123728321 is an apocalyptic number.

521123728321 is the 721889-th square number.

521123728321 is the 360945-th centered octagonal number.

It is an amenable number.

521123728321 is a deficient number, since it is larger than the sum of its proper divisors (88908617186).

521123728321 is an frugal number, since it uses more digits than its factorization.

521123728321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1310 (or 655 counting only the distinct ones).

The product of its digits is 40320, while the sum is 37.

The spelling of 521123728321 in words is "five hundred twenty-one billion, one hundred twenty-three million, seven hundred twenty-eight thousand, three hundred twenty-one".