721385 has 8 divisors (see below), whose sum is σ = 989376. Its totient is φ = 494640.

The previous prime is 721381. The next prime is 721387. The reversal of 721385 is 583127.

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

It is not a de Polignac number, because 721385 - 2² = 721381 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721385.

It is not an unprimeable number, because it can be changed into a prime (721381) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10271 + ... + 10340.

It is an arithmetic number, because the mean of its divisors is an integer number (123672).

2⁷²¹³⁸⁵ is an apocalyptic number.

It is an amenable number.

721385 is a deficient number, since it is larger than the sum of its proper divisors (267991).

721385 is a wasteful number, since it uses less digits than its factorization.

721385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20623.

The product of its digits is 1680, while the sum is 26.

The square root of 721385 is about 849.3438644036. The cubic root of 721385 is about 89.6855279870.

The spelling of 721385 in words is "seven hundred twenty-one thousand, three hundred eighty-five".