720989 has 4 divisors (see below), whose sum is σ = 729180. Its totient is φ = 712800.

The previous prime is 720983. The next prime is 720991. The reversal of 720989 is 989027.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 989027 = 13 ⋅76079.

It can be written as a sum of positive squares in 2 ways, for example, as 511225 + 209764 = 715^2 + 458^2 .

It is a cyclic number.

It is not a de Polignac number, because 720989 - 2¹⁶ = 655453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (720983) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3962 + ... + 4139.

It is an arithmetic number, because the mean of its divisors is an integer number (182295).

2⁷²⁰⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

720989 is a deficient number, since it is larger than the sum of its proper divisors (8191).

720989 is an equidigital number, since it uses as much as digits as its factorization.

720989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8190.

The product of its (nonzero) digits is 9072, while the sum is 35.

The square root of 720989 is about 849.1107112739. The cubic root of 720989 is about 89.6691142044.

It can be divided in two parts, 7209 and 89, that multiplied together give a square (641601 = 801²).

The spelling of 720989 in words is "seven hundred twenty thousand, nine hundred eighty-nine".