641609 has 4 divisors (see below), whose sum is σ = 657300. Its totient is φ = 625920.

The previous prime is 641581. The next prime is 641623. The reversal of 641609 is 906146.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 906146 = 2 ⋅453073.

It can be written as a sum of positive squares in 2 ways, for example, as 64009 + 577600 = 253^2 + 760^2 .

It is a cyclic number.

It is not a de Polignac number, because 641609 - 2¹² = 637513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (641639) 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, 7784 + ... + 7865.

It is an arithmetic number, because the mean of its divisors is an integer number (164325).

2⁶⁴¹⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

641609 is a deficient number, since it is larger than the sum of its proper divisors (15691).

641609 is a wasteful number, since it uses less digits than its factorization.

641609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15690.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 641609 is about 801.0049937422. The cubic root of 641609 is about 86.2495456113.

The spelling of 641609 in words is "six hundred forty-one thousand, six hundred nine".