721044 has 18 divisors (see below), whose sum is σ = 1822730. Its totient is φ = 240336.

The previous prime is 721043. The next prime is 721051. The reversal of 721044 is 440127.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 544644 + 176400 = 738^2 + 420^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721044.

It is not an unprimeable number, because it can be changed into a prime (721043) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 9979 + ... + 10050.

2⁷²¹⁰⁴⁴ is an apocalyptic number.

It is an amenable number.

721044 is an abundant number, since it is smaller than the sum of its proper divisors (1101686).

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

721044 is a wasteful number, since it uses less digits than its factorization.

721044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20039 (or 20034 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 18.

The square root of 721044 is about 849.1430974812. The cubic root of 721044 is about 89.6713942558.

The spelling of 721044 in words is "seven hundred twenty-one thousand, forty-four", and thus it is an iban number.