721240 has 64 divisors (see below), whose sum is σ = 1864800. Its totient is φ = 248832.

The previous prime is 721229. The next prime is 721243. The reversal of 721240 is 42127.

It is a d-powerful number, because it can be written as 7³ + 2¹⁷ + 2¹⁹ + 1 + 4⁸ + 0 .

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 pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9844 + ... + 9916.

2⁷²¹²⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (932400).

721240 is an abundant number, since it is smaller than the sum of its proper divisors (1143560).

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

721240 is a wasteful number, since it uses less digits than its factorization.

721240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116 (or 112 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 16.

The square root of 721240 is about 849.2585001047. The cubic root of 721240 is about 89.6795185871.

Adding to 721240 its reverse (42127), we get a palindrome (763367).

It can be divided in two parts, 721 and 240, that added together give a square (961 = 31²).

The spelling of 721240 in words is "seven hundred twenty-one thousand, two hundred forty", and thus it is an iban number.