721105 has 16 divisors (see below), whose sum is σ = 1079424. Its totient is φ = 449280.

The previous prime is 721087. The next prime is 721109. The reversal of 721105 is 501127.

It is not a de Polignac number, because 721105 - 2¹¹ = 719057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721109) 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 15 ways as a sum of consecutive naturals, for example, 552 + ... + 1321.

It is an arithmetic number, because the mean of its divisors is an integer number (67464).

2⁷²¹¹⁰⁵ is an apocalyptic number.

It is an amenable number.

721105 is a deficient number, since it is larger than the sum of its proper divisors (358319).

721105 is a wasteful number, since it uses less digits than its factorization.

721105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1896.

The product of its (nonzero) digits is 70, while the sum is 16.

The square root of 721105 is about 849.1790152848. The cubic root of 721105 is about 89.6739229044.

It can be divided in two parts, 7 and 21105, that added together give a palindrome (21112).

The spelling of 721105 in words is "seven hundred twenty-one thousand, one hundred five".