641657 has 4 divisors (see below), whose sum is σ = 645540. Its totient is φ = 637776.

The previous prime is 641639. The next prime is 641681. The reversal of 641657 is 756146.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 395641 + 246016 = 629^2 + 496^2 .

It is a cyclic number.

It is not a de Polignac number, because 641657 - 2¹⁸ = 379513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (641057) 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, 1682 + ... + 2027.

It is an arithmetic number, because the mean of its divisors is an integer number (161385).

2⁶⁴¹⁶⁵⁷ is an apocalyptic number.

It is an amenable number.

641657 is a deficient number, since it is larger than the sum of its proper divisors (3883).

641657 is a wasteful number, since it uses less digits than its factorization.

641657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3882.

The product of its digits is 5040, while the sum is 29.

The square root of 641657 is about 801.0349555419. The cubic root of 641657 is about 86.2516963890.

It can be divided in two parts, 6 and 41657, that multiplied together give a palindrome (249942).

The spelling of 641657 in words is "six hundred forty-one thousand, six hundred fifty-seven".