641621 has 4 divisors (see below), whose sum is σ = 643500. Its totient is φ = 639744.

The previous prime is 641581. The next prime is 641623. The reversal of 641621 is 126146.

It is a happy number.

641621 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 an emirpimes, since its reverse is a distinct semiprime: 126146 = 2 ⋅63073.

It can be written as a sum of positive squares in 2 ways, for example, as 192721 + 448900 = 439^2 + 670^2 .

It is a cyclic number.

It is not a de Polignac number, because 641621 - 2¹⁴ = 625237 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 641593 and 641602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641623) 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, 266 + ... + 1163.

It is an arithmetic number, because the mean of its divisors is an integer number (160875).

2⁶⁴¹⁶²¹ is an apocalyptic number.

It is an amenable number.

641621 is a deficient number, since it is larger than the sum of its proper divisors (1879).

641621 is a wasteful number, since it uses less digits than its factorization.

641621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1878.

The product of its digits is 288, while the sum is 20.

The square root of 641621 is about 801.0124842972. The cubic root of 641621 is about 86.2500833157.

Subtracting from 641621 its sum of digits (20), we obtain a square (641601 = 801²).

Adding to 641621 its reverse (126146), we get a palindrome (767767).

The spelling of 641621 in words is "six hundred forty-one thousand, six hundred twenty-one".