723821 has 8 divisors (see below), whose sum is σ = 843264. Its totient is φ = 608400.

The previous prime is 723803. The next prime is 723823. The reversal of 723821 is 128327.

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 723821 - 2¹⁰ = 722797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (723823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 605 + ... + 1346.

It is an arithmetic number, because the mean of its divisors is an integer number (105408).

2⁷²³⁸²¹ is an apocalyptic number.

It is an amenable number.

723821 is a deficient number, since it is larger than the sum of its proper divisors (119443).

723821 is a wasteful number, since it uses less digits than its factorization.

723821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2011.

The product of its digits is 672, while the sum is 23.

The square root of 723821 is about 850.7767039594. The cubic root of 723821 is about 89.7863657225.

The spelling of 723821 in words is "seven hundred twenty-three thousand, eight hundred twenty-one".