720915691 has 4 divisors (see below), whose sum is σ = 721876384. Its totient is φ = 719955000.

The previous prime is 720915677. The next prime is 720915707. The reversal of 720915691 is 196519027.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 196519027 = 41 ⋅4793147.

It is a cyclic number.

It is not a de Polignac number, because 720915691 - 2⁹ = 720915179 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (720915641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 479220 + ... + 480721.

It is an arithmetic number, because the mean of its divisors is an integer number (180469096).

Almost surely, 2^720915691 is an apocalyptic number.

720915691 is a deficient number, since it is larger than the sum of its proper divisors (960693).

720915691 is an equidigital number, since it uses as much as digits as its factorization.

720915691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 960692.

The product of its (nonzero) digits is 34020, while the sum is 40.

The square root of 720915691 is about 26849.8732026801. The cubic root of 720915691 is about 896.6607496435.

The spelling of 720915691 in words is "seven hundred twenty million, nine hundred fifteen thousand, six hundred ninety-one".