729531521 has 4 divisors (see below), whose sum is σ = 729775872. Its totient is φ = 729287172.

The previous prime is 729531449. The next prime is 729531527. The reversal of 729531521 is 125135927.

729531521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 125135927 = 7 ⋅17876561.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-729531521 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (729531527) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 117641 + ... + 123686.

It is an arithmetic number, because the mean of its divisors is an integer number (182443968).

Almost surely, 2^729531521 is an apocalyptic number.

It is an amenable number.

729531521 is a deficient number, since it is larger than the sum of its proper divisors (244351).

729531521 is a wasteful number, since it uses less digits than its factorization.

729531521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244350.

The product of its digits is 18900, while the sum is 35.

The square root of 729531521 is about 27009.8411879818. The cubic root of 729531521 is about 900.2186797832.

The spelling of 729531521 in words is "seven hundred twenty-nine million, five hundred thirty-one thousand, five hundred twenty-one".