640121 has 2 divisors, whose sum is σ = 640122. Its totient is φ = 640120.

The previous prime is 640109. The next prime is 640127. The reversal of 640121 is 121046.

640121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 640000 + 121 = 800^2 + 11^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640121 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 640096 and 640105.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640121.

It is not a weakly prime, because it can be changed into another prime (640127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320060 + 320061.

It is an arithmetic number, because the mean of its divisors is an integer number (320061).

2⁶⁴⁰¹²¹ is an apocalyptic number.

It is an amenable number.

640121 is a deficient number, since it is larger than the sum of its proper divisors (1).

640121 is an equidigital number, since it uses as much as digits as its factorization.

640121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 640121 is about 800.0756214259. The cubic root of 640121 is about 86.1828182298.

Adding to 640121 its reverse (121046), we get a palindrome (761167).

It can be divided in two parts, 6401 and 21, that multiplied together give a triangular number (134421 = T₅₁₈).

The spelling of 640121 in words is "six hundred forty thousand, one hundred twenty-one".