721670 has 8 divisors (see below), whose sum is σ = 1299024. Its totient is φ = 288664.

The previous prime is 721663. The next prime is 721687. The reversal of 721670 is 76127.

It is a happy number.

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

It is an Ulam number.

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

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 721670.

It is an unprimeable number.

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, 36074 + ... + 36093.

It is an arithmetic number, because the mean of its divisors is an integer number (162378).

2⁷²¹⁶⁷⁰ is an apocalyptic number.

721670 is a deficient number, since it is larger than the sum of its proper divisors (577354).

721670 is a wasteful number, since it uses less digits than its factorization.

721670 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72174.

The product of its (nonzero) digits is 588, while the sum is 23.

The square root of 721670 is about 849.5116244055. The cubic root of 721670 is about 89.6973372198.

Adding to 721670 its reverse (76127), we get a palindrome (797797).

The spelling of 721670 in words is "seven hundred twenty-one thousand, six hundred seventy".