660648491 has 2 divisors, whose sum is σ = 660648492. Its totient is φ = 660648490.

The previous prime is 660648479. The next prime is 660648523. The reversal of 660648491 is 194846066.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 660648491 - 2¹⁰ = 660647467 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (660648091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330324245 + 330324246.

It is an arithmetic number, because the mean of its divisors is an integer number (330324246).

Almost surely, 2^660648491 is an apocalyptic number.

660648491 is a deficient number, since it is larger than the sum of its proper divisors (1).

660648491 is an equidigital number, since it uses as much as digits as its factorization.

660648491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 248832, while the sum is 44.

The square root of 660648491 is about 25703.0832975346. The cubic root of 660648491 is about 870.9438345486.

The spelling of 660648491 in words is "six hundred sixty million, six hundred forty-eight thousand, four hundred ninety-one".