663523561 has 2 divisors, whose sum is σ = 663523562. Its totient is φ = 663523560.

The previous prime is 663523559. The next prime is 663523577. The reversal of 663523561 is 165325366.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 463583961 + 199939600 = 21531^2 + 14140^2 .

It is a cyclic number.

It is not a de Polignac number, because 663523561 - 2¹ = 663523559 is a prime.

Together with 663523559, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 663523561.

It is not a weakly prime, because it can be changed into another prime (663523501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 331761780 + 331761781.

It is an arithmetic number, because the mean of its divisors is an integer number (331761781).

Almost surely, 2^663523561 is an apocalyptic number.

It is an amenable number.

663523561 is a deficient number, since it is larger than the sum of its proper divisors (1).

663523561 is an equidigital number, since it uses as much as digits as its factorization.

663523561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 97200, while the sum is 37.

The square root of 663523561 is about 25758.9510850112. The cubic root of 663523561 is about 872.2054236627.

The spelling of 663523561 in words is "six hundred sixty-three million, five hundred twenty-three thousand, five hundred sixty-one".