729921 has 8 divisors (see below), whose sum is σ = 977184. Its totient is φ = 484640.

The previous prime is 729919. The next prime is 729931. The reversal of 729921 is 129927.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 729921 - 2¹ = 729919 is a prime.

It is an Ulam number.

729921 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (729931) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1141 + ... + 1661.

It is an arithmetic number, because the mean of its divisors is an integer number (122148).

2⁷²⁹⁹²¹ is an apocalyptic number.

It is an amenable number.

729921 is a deficient number, since it is larger than the sum of its proper divisors (247263).

729921 is a wasteful number, since it uses less digits than its factorization.

729921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 991.

The product of its digits is 2268, while the sum is 30.

The square root of 729921 is about 854.3541420278. The cubic root of 729921 is about 90.0378852846.

The spelling of 729921 in words is "seven hundred twenty-nine thousand, nine hundred twenty-one".