521605663 has 2 divisors, whose sum is σ = 521605664. Its totient is φ = 521605662.

The previous prime is 521605639. The next prime is 521605709. The reversal of 521605663 is 366506125.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 521605663 - 2¹³ = 521597471 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521605603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260802831 + 260802832.

It is an arithmetic number, because the mean of its divisors is an integer number (260802832).

Almost surely, 2^521605663 is an apocalyptic number.

521605663 is a deficient number, since it is larger than the sum of its proper divisors (1).

521605663 is an equidigital number, since it uses as much as digits as its factorization.

521605663 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32400, while the sum is 34.

The square root of 521605663 is about 22838.6878563546. The cubic root of 521605663 is about 804.9719846737.

The spelling of 521605663 in words is "five hundred twenty-one million, six hundred five thousand, six hundred sixty-three".