720781 has 4 divisors (see below), whose sum is σ = 744064. Its totient is φ = 697500.

The previous prime is 720779. The next prime is 720791. The reversal of 720781 is 187027.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 720781 - 2¹ = 720779 is a prime.

It is a super-2 number, since 2×720781² = 1039050499922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (720791) 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, 11595 + ... + 11656.

It is an arithmetic number, because the mean of its divisors is an integer number (186016).

2⁷²⁰⁷⁸¹ is an apocalyptic number.

It is an amenable number.

720781 is a deficient number, since it is larger than the sum of its proper divisors (23283).

720781 is a wasteful number, since it uses less digits than its factorization.

720781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23282.

The product of its (nonzero) digits is 784, while the sum is 25.

The square root of 720781 is about 848.9882213553. The cubic root of 720781 is about 89.6604904160.

The spelling of 720781 in words is "seven hundred twenty thousand, seven hundred eighty-one".