657705661 has 2 divisors, whose sum is σ = 657705662. Its totient is φ = 657705660.

The previous prime is 657705647. The next prime is 657705667. The reversal of 657705661 is 166507756.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 425143161 + 232562500 = 20619^2 + 15250^2 .

It is a cyclic number.

It is not a de Polignac number, because 657705661 - 2¹⁵ = 657672893 is a prime.

It is a super-2 number, since 2×657705661² = 865153473022893842, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (657705667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328852830 + 328852831.

It is an arithmetic number, because the mean of its divisors is an integer number (328852831).

Almost surely, 2^657705661 is an apocalyptic number.

It is an amenable number.

657705661 is a deficient number, since it is larger than the sum of its proper divisors (1).

657705661 is an equidigital number, since it uses as much as digits as its factorization.

657705661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 264600, while the sum is 43.

The square root of 657705661 is about 25645.7727705757. The cubic root of 657705661 is about 869.6487158003.

The spelling of 657705661 in words is "six hundred fifty-seven million, seven hundred five thousand, six hundred sixty-one".