721611 has 24 divisors (see below), whose sum is σ = 1173744. Its totient is φ = 423360.

The previous prime is 721597. The next prime is 721613. The reversal of 721611 is 116127.

It is not a de Polignac number, because 721611 - 2⁶ = 721547 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721613) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3565 + ... + 3761.

It is an arithmetic number, because the mean of its divisors is an integer number (48906).

2⁷²¹⁶¹¹ is an apocalyptic number.

721611 is a deficient number, since it is larger than the sum of its proper divisors (452133).

721611 is a wasteful number, since it uses less digits than its factorization.

721611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 251 (or 248 counting only the distinct ones).

The product of its digits is 84, while the sum is 18.

The square root of 721611 is about 849.4768978613. The cubic root of 721611 is about 89.6948927566.

Adding to 721611 its reverse (116127), we get a palindrome (837738).

It can be divided in two parts, 7216 and 11, that added together give a palindrome (7227).

The spelling of 721611 in words is "seven hundred twenty-one thousand, six hundred eleven".