721166 has 8 divisors (see below), whose sum is σ = 1091664. Its totient is φ = 357280.

The previous prime is 721163. The next prime is 721169. The reversal of 721166 is 661127.

It is an interprime number because it is at equal distance from previous prime (721163) and next prime (721169).

It is a sphenic number, since it is the product of 3 distinct primes.

It is an Ulam number.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721166.

It is not an unprimeable number, because it can be changed into a prime (721163) 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 3 ways as a sum of consecutive naturals, for example, 1370 + ... + 1821.

It is an arithmetic number, because the mean of its divisors is an integer number (136458).

2⁷²¹¹⁶⁶ is an apocalyptic number.

721166 is a deficient number, since it is larger than the sum of its proper divisors (370498).

721166 is a wasteful number, since it uses less digits than its factorization.

721166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3306.

The product of its digits is 504, while the sum is 23.

The square root of 721166 is about 849.2149315692. The cubic root of 721166 is about 89.6764514105.

The spelling of 721166 in words is "seven hundred twenty-one thousand, one hundred sixty-six".