20604523661 has 2 divisors, whose sum is σ = 20604523662. Its totient is φ = 20604523660.

The previous prime is 20604523631. The next prime is 20604523663. The reversal of 20604523661 is 16632540602.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19962864100 + 641659561 = 141290^2 + 25331^2 .

It is a cyclic number.

It is not a de Polignac number, because 20604523661 - 2²⁶ = 20537414797 is a prime.

Together with 20604523663, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20604523663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10302261830 + 10302261831.

It is an arithmetic number, because the mean of its divisors is an integer number (10302261831).

Almost surely, 2^20604523661 is an apocalyptic number.

It is an amenable number.

20604523661 is a deficient number, since it is larger than the sum of its proper divisors (1).

20604523661 is an equidigital number, since it uses as much as digits as its factorization.

20604523661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 51840, while the sum is 35.

The spelling of 20604523661 in words is "twenty billion, six hundred four million, five hundred twenty-three thousand, six hundred sixty-one".