723440 has 20 divisors (see below), whose sum is σ = 1682184. Its totient is φ = 289344.

The previous prime is 723439. The next prime is 723451. The reversal of 723440 is 44327.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4442 + ... + 4601.

2⁷²³⁴⁴⁰ is an apocalyptic number.

It is an amenable number.

723440 is an abundant number, since it is smaller than the sum of its proper divisors (958744).

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

723440 is a wasteful number, since it uses less digits than its factorization.

723440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9056 (or 9050 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 20.

The square root of 723440 is about 850.5527614440. The cubic root of 723440 is about 89.7706092444.

Adding to 723440 its reverse (44327), we get a palindrome (767767).

The spelling of 723440 in words is "seven hundred twenty-three thousand, four hundred forty", and thus it is an iban number.