840121 has 4 divisors (see below), whose sum is σ = 876672. Its totient is φ = 803572.

The previous prime is 840109. The next prime is 840137. The reversal of 840121 is 121048.

It is a happy number.

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 840121 - 2⁹ = 839609 is a prime.

It is a Duffinian number.

840121 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 840095 and 840104.

It is not an unprimeable number, because it can be changed into a prime (840181) 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, 18241 + ... + 18286.

It is an arithmetic number, because the mean of its divisors is an integer number (219168).

2⁸⁴⁰¹²¹ is an apocalyptic number.

It is an amenable number.

840121 is a deficient number, since it is larger than the sum of its proper divisors (36551).

840121 is a wasteful number, since it uses less digits than its factorization.

840121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36550.

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 840121 is about 916.5811475260. The cubic root of 840121 is about 94.3584098727.

Adding to 840121 its reverse (121048), we get a palindrome (961169).

It can be divided in two parts, 840 and 121, that added together give a square (961 = 31²).

The spelling of 840121 in words is "eight hundred forty thousand, one hundred twenty-one".