721045 has 8 divisors (see below), whose sum is σ = 931896. Its totient is φ = 532416.

The previous prime is 721043. The next prime is 721051. The reversal of 721045 is 540127.

It can be written as a sum of positive squares in 4 ways, for example, as 66564 + 654481 = 258^2 + 809^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 721045 - 2¹ = 721043 is a prime.

It is a Duffinian number.

721045 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721043) 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 7 ways as a sum of consecutive naturals, for example, 5482 + ... + 5611.

It is an arithmetic number, because the mean of its divisors is an integer number (116487).

2⁷²¹⁰⁴⁵ is an apocalyptic number.

It is an amenable number.

721045 is a deficient number, since it is larger than the sum of its proper divisors (210851).

721045 is a wasteful number, since it uses less digits than its factorization.

721045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11111.

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 721045 is about 849.1436863099. The cubic root of 721045 is about 89.6714357102.

The spelling of 721045 in words is "seven hundred twenty-one thousand, forty-five".