817421 has 4 divisors (see below), whose sum is σ = 891744. Its totient is φ = 743100.

The previous prime is 817409. The next prime is 817433. The reversal of 817421 is 124718.

817421 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.

It is an interprime number because it is at equal distance from previous prime (817409) and next prime (817433).

It is a cyclic number.

It is not a de Polignac number, because 817421 - 2⁶ = 817357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (817321) 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, 37145 + ... + 37166.

It is an arithmetic number, because the mean of its divisors is an integer number (222936).

2⁸¹⁷⁴²¹ is an apocalyptic number.

It is an amenable number.

817421 is a deficient number, since it is larger than the sum of its proper divisors (74323).

817421 is a wasteful number, since it uses less digits than its factorization.

817421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74322.

The product of its digits is 448, while the sum is 23.

The square root of 817421 is about 904.1133778459. The cubic root of 817421 is about 93.5007864042.

The spelling of 817421 in words is "eight hundred seventeen thousand, four hundred twenty-one".