721698 has 8 divisors (see below), whose sum is σ = 1443408. Its totient is φ = 240564.

The previous prime is 721697. The next prime is 721703. The reversal of 721698 is 896127.

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

721698 is an admirable number.

It is an alternating number because its digits alternate between odd and even.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (721697) 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, 60136 + ... + 60147.

It is an arithmetic number, because the mean of its divisors is an integer number (180426).

2⁷²¹⁶⁹⁸ is an apocalyptic number.

721698 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

721698 is a wasteful number, since it uses less digits than its factorization.

721698 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 120288.

The product of its digits is 6048, while the sum is 33.

The square root of 721698 is about 849.5281043026. The cubic root of 721698 is about 89.6984972574.

It can be divided in two parts, 72 and 1698, that added together give a triangular number (1770 = T₅₉).

The spelling of 721698 in words is "seven hundred twenty-one thousand, six hundred ninety-eight".