721121 has 8 divisors (see below), whose sum is σ = 750720. Its totient is φ = 692208.

The previous prime is 721117. The next prime is 721129. The reversal of 721121 is 121127.

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 721121 - 2² = 721117 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 721096 and 721105.

It is not an unprimeable number, because it can be changed into a prime (721129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3035 + ... + 3263.

It is an arithmetic number, because the mean of its divisors is an integer number (93840).

2⁷²¹¹²¹ is an apocalyptic number.

It is an amenable number.

721121 is a deficient number, since it is larger than the sum of its proper divisors (29599).

721121 is a wasteful number, since it uses less digits than its factorization.

721121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 343.

The product of its digits is 28, while the sum is 14.

The square root of 721121 is about 849.1884360965. The cubic root of 721121 is about 89.6745861329.

Adding to 721121 its reverse (121127), we get a palindrome (842248).

The spelling of 721121 in words is "seven hundred twenty-one thousand, one hundred twenty-one", and thus it is an iban number.