720891 has 12 divisors (see below), whose sum is σ = 1049568. Its totient is φ = 476784.

The previous prime is 720887. The next prime is 720899. The reversal of 720891 is 198027.

It is not a de Polignac number, because 720891 - 2² = 720887 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

720891 is a modest number, since divided by 891 gives 72 as remainder.

It is not an unprimeable number, because it can be changed into a prime (720899) 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 11 ways as a sum of consecutive naturals, for example, 1326 + ... + 1788.

It is an arithmetic number, because the mean of its divisors is an integer number (87464).

2⁷²⁰⁸⁹¹ is an apocalyptic number.

720891 is a deficient number, since it is larger than the sum of its proper divisors (328677).

720891 is a wasteful number, since it uses less digits than its factorization.

720891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 642 (or 639 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 720891 is about 849.0530018792. The cubic root of 720891 is about 89.6650512800.

The spelling of 720891 in words is "seven hundred twenty thousand, eight hundred ninety-one".