721245 has 16 divisors (see below), whose sum is σ = 1319040. Its totient is φ = 329664.

The previous prime is 721243. The next prime is 721261. The reversal of 721245 is 542127.

It is not a de Polignac number, because 721245 - 2¹ = 721243 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a d-powerful number, because it can be written as 7³ + 2¹⁷ + 2¹⁹ + 1 + 4⁸ + 5 .

721245 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721243) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3330 + ... + 3539.

It is an arithmetic number, because the mean of its divisors is an integer number (82440).

2⁷²¹²⁴⁵ is an apocalyptic number.

It is an amenable number.

721245 is a deficient number, since it is larger than the sum of its proper divisors (597795).

721245 is a wasteful number, since it uses less digits than its factorization.

721245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6884.

The product of its digits is 560, while the sum is 21.

The square root of 721245 is about 849.2614438440. The cubic root of 721245 is about 89.6797258211.

The spelling of 721245 in words is "seven hundred twenty-one thousand, two hundred forty-five".