656640331 has 2 divisors, whose sum is σ = 656640332. Its totient is φ = 656640330.

The previous prime is 656640287. The next prime is 656640343. The reversal of 656640331 is 133046656.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 656640331 - 2¹³ = 656632139 is a prime.

It is a super-2 number, since 2×656640331² = 862353048591579122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (656640371) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328320165 + 328320166.

It is an arithmetic number, because the mean of its divisors is an integer number (328320166).

Almost surely, 2^656640331 is an apocalyptic number.

656640331 is a deficient number, since it is larger than the sum of its proper divisors (1).

656640331 is an equidigital number, since it uses as much as digits as its factorization.

656640331 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 34.

The square root of 656640331 is about 25624.9942634140. The cubic root of 656640331 is about 869.1789192586.

Adding to 656640331 its reverse (133046656), we get a palindrome (789686987).

The spelling of 656640331 in words is "six hundred fifty-six million, six hundred forty thousand, three hundred thirty-one".