721115 has 4 divisors (see below), whose sum is σ = 865344. Its totient is φ = 576888.

The previous prime is 721111. The next prime is 721117. The reversal of 721115 is 511127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 511127 = 89 ⋅5743.

It is a cyclic number.

It is not a de Polignac number, because 721115 - 2² = 721111 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 721093 and 721102.

It is not an unprimeable number, because it can be changed into a prime (721111) 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, 72107 + ... + 72116.

It is an arithmetic number, because the mean of its divisors is an integer number (216336).

2⁷²¹¹¹⁵ is an apocalyptic number.

721115 is a deficient number, since it is larger than the sum of its proper divisors (144229).

721115 is a wasteful number, since it uses less digits than its factorization.

721115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144228.

The product of its digits is 70, while the sum is 17.

The square root of 721115 is about 849.1849033043. The cubic root of 721115 is about 89.6743374234.

The spelling of 721115 in words is "seven hundred twenty-one thousand, one hundred fifteen".