720691 has 4 divisors (see below), whose sum is σ = 727792. Its totient is φ = 713592.

The previous prime is 720683. The next prime is 720697. The reversal of 720691 is 196027.

720691 = T₆₃ + T₆₄ + ... + T₁₆₅.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 720691 - 2³ = 720683 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (720697) 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, 3396 + ... + 3601.

It is an arithmetic number, because the mean of its divisors is an integer number (181948).

2⁷²⁰⁶⁹¹ is an apocalyptic number.

720691 is a deficient number, since it is larger than the sum of its proper divisors (7101).

720691 is a wasteful number, since it uses less digits than its factorization.

720691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7100.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 720691 is about 848.9352154317. The cubic root of 720691 is about 89.6567584549.

The spelling of 720691 in words is "seven hundred twenty thousand, six hundred ninety-one".