721091 has 8 divisors (see below), whose sum is σ = 850944. Its totient is φ = 597960.

The previous prime is 721087. The next prime is 721109. The reversal of 721091 is 190127.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 721091 - 2² = 721087 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721091.

It is not an unprimeable number, because it can be changed into a prime (721051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1445 + ... + 1878.

It is an arithmetic number, because the mean of its divisors is an integer number (106368).

2⁷²¹⁰⁹¹ is an apocalyptic number.

721091 is a deficient number, since it is larger than the sum of its proper divisors (129853).

721091 is a wasteful number, since it uses less digits than its factorization.

721091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3361.

The product of its (nonzero) digits is 126, while the sum is 20.

The square root of 721091 is about 849.1707719888. The cubic root of 721091 is about 89.6733425714.

The spelling of 721091 in words is "seven hundred twenty-one thousand, ninety-one".