840421 has 8 divisors (see below), whose sum is σ = 870264. Its totient is φ = 811200.

The previous prime is 840353. The next prime is 840439. The reversal of 840421 is 124048.

It can be written as a sum of positive squares in 4 ways, for example, as 343396 + 497025 = 586^2 + 705^2 .

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 840421 - 2¹⁷ = 709349 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 (840451) 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 7 ways as a sum of consecutive naturals, for example, 5275 + ... + 5431.

It is an arithmetic number, because the mean of its divisors is an integer number (108783).

2⁸⁴⁰⁴²¹ is an apocalyptic number.

It is an amenable number.

840421 is a deficient number, since it is larger than the sum of its proper divisors (29843).

840421 is a wasteful number, since it uses less digits than its factorization.

840421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 311.

The product of its (nonzero) digits is 256, while the sum is 19.

The square root of 840421 is about 916.7447845502. The cubic root of 840421 is about 94.3696400622.

Adding to 840421 its reverse (124048), we get a palindrome (964469).

The spelling of 840421 in words is "eight hundred forty thousand, four hundred twenty-one".