656121 has 16 divisors (see below), whose sum is σ = 941184. Its totient is φ = 405504.

The previous prime is 656119. The next prime is 656129. The reversal of 656121 is 121656.

It is a happy number.

It is not a de Polignac number, because 656121 - 2¹ = 656119 is a prime.

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

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 656121.

It is not an unprimeable number, because it can be changed into a prime (656129) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2425 + ... + 2681.

It is an arithmetic number, because the mean of its divisors is an integer number (58824).

2⁶⁵⁶¹²¹ is an apocalyptic number.

It is an amenable number.

656121 is a deficient number, since it is larger than the sum of its proper divisors (285063).

656121 is a wasteful number, since it uses less digits than its factorization.

656121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320.

The product of its digits is 360, while the sum is 21.

The square root of 656121 is about 810.0129628592. The cubic root of 656121 is about 86.8949716863.

Subtracting from 656121 its sum of digits (21), we obtain a square (656100 = 810²).

Adding to 656121 its reverse (121656), we get a palindrome (777777).

It can be divided in two parts, 656 and 121, that added together give a palindrome (777).

The spelling of 656121 in words is "six hundred fifty-six thousand, one hundred twenty-one".