663602561 has 2 divisors, whose sum is σ = 663602562. Its totient is φ = 663602560.

The previous prime is 663602549. The next prime is 663602567. The reversal of 663602561 is 165206366.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 448804225 + 214798336 = 21185^2 + 14656^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-663602561 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (663602567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 331801280 + 331801281.

It is an arithmetic number, because the mean of its divisors is an integer number (331801281).

Almost surely, 2^663602561 is an apocalyptic number.

It is an amenable number.

663602561 is a deficient number, since it is larger than the sum of its proper divisors (1).

663602561 is an equidigital number, since it uses as much as digits as its factorization.

663602561 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 35.

The square root of 663602561 is about 25760.4844869036. The cubic root of 663602561 is about 872.2400376026.

It can be divided in two parts, 66360 and 2561, that added together give a cube (68921 = 41³).

The spelling of 663602561 in words is "six hundred sixty-three million, six hundred two thousand, five hundred sixty-one".