721628 has 12 divisors (see below), whose sum is σ = 1270080. Its totient is φ = 358752.

The previous prime is 721621. The next prime is 721631. The reversal of 721628 is 826127.

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 721597 and 721606.

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 721628.

It is not an unprimeable number, because it can be changed into a prime (721621) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 488 + ... + 1296.

It is an arithmetic number, because the mean of its divisors is an integer number (105840).

2⁷²¹⁶²⁸ is an apocalyptic number.

It is an amenable number.

721628 is a deficient number, since it is larger than the sum of its proper divisors (548452).

721628 is a wasteful number, since it uses less digits than its factorization.

721628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1036 (or 1034 counting only the distinct ones).

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

The square root of 721628 is about 849.4869039603. The cubic root of 721628 is about 89.6955971071.

The spelling of 721628 in words is "seven hundred twenty-one thousand, six hundred twenty-eight".