729808721 has 4 divisors (see below), whose sum is σ = 729864000. Its totient is φ = 729753444.

The previous prime is 729808687. The next prime is 729808741. The reversal of 729808721 is 127808927.

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 a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-729808721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (729808741) 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, 5060 + ... + 38538.

It is an arithmetic number, because the mean of its divisors is an integer number (182466000).

Almost surely, 2^729808721 is an apocalyptic number.

It is an amenable number.

729808721 is a deficient number, since it is larger than the sum of its proper divisors (55279).

729808721 is a wasteful number, since it uses less digits than its factorization.

729808721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55278.

The product of its (nonzero) digits is 112896, while the sum is 44.

The square root of 729808721 is about 27014.9721635985. The cubic root of 729808721 is about 900.3326840045.

The spelling of 729808721 in words is "seven hundred twenty-nine million, eight hundred eight thousand, seven hundred twenty-one".