810721 has 4 divisors (see below), whose sum is σ = 812592. Its totient is φ = 808852.

The previous prime is 810697. The next prime is 810737. The reversal of 810721 is 127018.

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 a cyclic number.

It is not a de Polignac number, because 810721 - 2⁹ = 810209 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (810791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 90 + ... + 1276.

It is an arithmetic number, because the mean of its divisors is an integer number (203148).

2⁸¹⁰⁷²¹ is an apocalyptic number.

It is an amenable number.

810721 is a deficient number, since it is larger than the sum of its proper divisors (1871).

810721 is a wasteful number, since it uses less digits than its factorization.

810721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1870.

The product of its (nonzero) digits is 112, while the sum is 19.

The square root of 810721 is about 900.4004664592. The cubic root of 810721 is about 93.2446251817.

Adding to 810721 its reverse (127018), we get a palindrome (937739).

It can be divided in two parts, 8107 and 21, that added together give a triangular number (8128 = T₁₂₇).

The spelling of 810721 in words is "eight hundred ten thousand, seven hundred twenty-one".