731005721 has 4 divisors (see below), whose sum is σ = 741019572. Its totient is φ = 720991872.

The previous prime is 731005657. The next prime is 731005747. The reversal of 731005721 is 127500137.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 490135321 + 240870400 = 22139^2 + 15520^2 .

It is a cyclic number.

It is not a de Polignac number, because 731005721 - 2⁶ = 731005657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (731005621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5006816 + ... + 5006961.

It is an arithmetic number, because the mean of its divisors is an integer number (185254893).

Almost surely, 2^731005721 is an apocalyptic number.

It is an amenable number.

731005721 is a deficient number, since it is larger than the sum of its proper divisors (10013851).

731005721 is a wasteful number, since it uses less digits than its factorization.

731005721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10013850.

The product of its (nonzero) digits is 1470, while the sum is 26.

The square root of 731005721 is about 27037.1174683989. The cubic root of 731005721 is about 900.8246437607.

Adding to 731005721 its reverse (127500137), we get a palindrome (858505858).

The spelling of 731005721 in words is "seven hundred thirty-one million, five thousand, seven hundred twenty-one".