813521 has 4 divisors (see below), whose sum is σ = 821232. Its totient is φ = 805812.

The previous prime is 813511. The next prime is 813529. The reversal of 813521 is 125318.

813521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 125318 = 2 ⋅62659.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-813521 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 813493 and 813502.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 813521.

It is not an unprimeable number, because it can be changed into a prime (813529) 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, 3695 + ... + 3908.

It is an arithmetic number, because the mean of its divisors is an integer number (205308).

2⁸¹³⁵²¹ is an apocalyptic number.

It is an amenable number.

813521 is a deficient number, since it is larger than the sum of its proper divisors (7711).

813521 is a wasteful number, since it uses less digits than its factorization.

813521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7710.

The product of its digits is 240, while the sum is 20.

The square root of 813521 is about 901.9539899574. The cubic root of 813521 is about 93.3518486510.

Adding to 813521 its reverse (125318), we get a palindrome (938839).

The spelling of 813521 in words is "eight hundred thirteen thousand, five hundred twenty-one".