657641 has 4 divisors (see below), whose sum is σ = 668484. Its totient is φ = 646800.

The previous prime is 657617. The next prime is 657649. The reversal of 657641 is 146756.

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 87616 + 570025 = 296^2 + 755^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-657641 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (657649) 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, 5330 + ... + 5451.

It is an arithmetic number, because the mean of its divisors is an integer number (167121).

2⁶⁵⁷⁶⁴¹ is an apocalyptic number.

657641 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

657641 is a deficient number, since it is larger than the sum of its proper divisors (10843).

657641 is a wasteful number, since it uses less digits than its factorization.

657641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10842.

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

The square root of 657641 is about 810.9506766752. The cubic root of 657641 is about 86.9620215616.

The spelling of 657641 in words is "six hundred fifty-seven thousand, six hundred forty-one".