39643688561 has 2 divisors, whose sum is σ = 39643688562. Its totient is φ = 39643688560.

The previous prime is 39643688531. The next prime is 39643688563. The reversal of 39643688561 is 16588634693.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 22994689600 + 16648998961 = 151640^2 + 129031^2 .

It is an emirp because it is prime and its reverse (16588634693) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 39643688561 - 2¹⁴ = 39643672177 is a prime.

Together with 39643688563, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 39643688561.

It is not a weakly prime, because it can be changed into another prime (39643688563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19821844280 + 19821844281.

It is an arithmetic number, because the mean of its divisors is an integer number (19821844281).

Almost surely, 2^39643688561 is an apocalyptic number.

It is an amenable number.

39643688561 is a deficient number, since it is larger than the sum of its proper divisors (1).

39643688561 is an equidigital number, since it uses as much as digits as its factorization.

39643688561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22394880, while the sum is 59.

The spelling of 39643688561 in words is "thirty-nine billion, six hundred forty-three million, six hundred eighty-eight thousand, five hundred sixty-one".