721740 has 48 divisors (see below), whose sum is σ = 2112768. Its totient is φ = 183744.

The previous prime is 721739. The next prime is 721783. The reversal of 721740 is 47127.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1119 + ... + 1641.

It is an arithmetic number, because the mean of its divisors is an integer number (44016).

2⁷²¹⁷⁴⁰ 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 721740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1056384).

721740 is an abundant number, since it is smaller than the sum of its proper divisors (1391028).

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

721740 is a wasteful number, since it uses less digits than its factorization.

721740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 558 (or 556 counting only the distinct ones).

The product of its (nonzero) digits is 392, while the sum is 21.

The square root of 721740 is about 849.5528235490. The cubic root of 721740 is about 89.7002372575.

Adding to 721740 its reverse (47127), we get a palindrome (768867).

The spelling of 721740 in words is "seven hundred twenty-one thousand, seven hundred forty", and thus it is an iban number.