39505537681 has 2 divisors, whose sum is σ = 39505537682. Its totient is φ = 39505537680.

The previous prime is 39505537507. The next prime is 39505537733. The reversal of 39505537681 is 18673550593.

It is an a-pointer prime, because the next prime (39505537733) can be obtained adding 39505537681 to its sum of digits (52).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 39505537600 + 81 = 198760^2 + 9^2 .

It is a cyclic number.

It is not a de Polignac number, because 39505537681 - 2¹⁹ = 39505013393 is a prime.

It is a super-2 number, since 2×39505537681² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (39505537781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19752768840 + 19752768841.

It is an arithmetic number, because the mean of its divisors is an integer number (19752768841).

Almost surely, 2^39505537681 is an apocalyptic number.

It is an amenable number.

39505537681 is a deficient number, since it is larger than the sum of its proper divisors (1).

39505537681 is an equidigital number, since it uses as much as digits as its factorization.

39505537681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3402000, while the sum is 52.

It can be divided in two parts, 395055376 and 81, that multiplied together give a square (31999485456 = 178884²).

The spelling of 39505537681 in words is "thirty-nine billion, five hundred five million, five hundred thirty-seven thousand, six hundred eighty-one".