665646643 has 2 divisors, whose sum is σ = 665646644. Its totient is φ = 665646642.

The previous prime is 665646593. The next prime is 665646677. The reversal of 665646643 is 346646566.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665646643 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 665646593 and 665646602.

It is not a weakly prime, because it can be changed into another prime (665646343) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332823321 + 332823322.

It is an arithmetic number, because the mean of its divisors is an integer number (332823322).

Almost surely, 2^665646643 is an apocalyptic number.

665646643 is a deficient number, since it is larger than the sum of its proper divisors (1).

665646643 is an equidigital number, since it uses as much as digits as its factorization.

665646643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1866240, while the sum is 46.

The square root of 665646643 is about 25800.1287399889. The cubic root of 665646643 is about 873.1347009397.

The spelling of 665646643 in words is "six hundred sixty-five million, six hundred forty-six thousand, six hundred forty-three".