721826 has 16 divisors (see below), whose sum is σ = 1264896. Its totient is φ = 302496.

The previous prime is 721793. The next prime is 721843. The reversal of 721826 is 628127.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 721795 and 721804.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721826.

It is an unprimeable number.

721826 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 110 + ... + 1206.

It is an arithmetic number, because the mean of its divisors is an integer number (79056).

2⁷²¹⁸²⁶ is an apocalyptic number.

721826 is a deficient number, since it is larger than the sum of its proper divisors (543070).

721826 is a wasteful number, since it uses less digits than its factorization.

721826 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1153.

The product of its digits is 1344, while the sum is 26.

The square root of 721826 is about 849.6034369045. The cubic root of 721826 is about 89.7037999042.

The spelling of 721826 in words is "seven hundred twenty-one thousand, eight hundred twenty-six".