39815506561 has 2 divisors, whose sum is σ = 39815506562. Its totient is φ = 39815506560.

The previous prime is 39815506537. The next prime is 39815506567. The reversal of 39815506561 is 16560551893.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 24415937536 + 15399569025 = 156256^2 + 124095^2 .

It is a cyclic number.

It is not a de Polignac number, because 39815506561 - 2²¹ = 39813409409 is a prime.

It is not a weakly prime, because it can be changed into another prime (39815506567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19907753280 + 19907753281.

It is an arithmetic number, because the mean of its divisors is an integer number (19907753281).

Almost surely, 2^39815506561 is an apocalyptic number.

It is an amenable number.

39815506561 is a deficient number, since it is larger than the sum of its proper divisors (1).

39815506561 is an equidigital number, since it uses as much as digits as its factorization.

39815506561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972000, while the sum is 49.

The spelling of 39815506561 in words is "thirty-nine billion, eight hundred fifteen million, five hundred six thousand, five hundred sixty-one".