39661427815681 has 4 divisors (see below), whose sum is σ = 45327346075072. Its totient is φ = 33995509556292.

The previous prime is 39661427815643. The next prime is 39661427815699. The reversal of 39661427815681 is 18651872416693.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 39661427815681 - 2³³ = 39652837881089 is a prime.

It is a super-2 number, since 2×39661427815681² (a number of 28 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (39661427815181) 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 in 3 ways as a sum of consecutive naturals, for example, 2832959129685 + ... + 2832959129698.

It is an arithmetic number, because the mean of its divisors is an integer number (11331836518768).

Almost surely, 2^{39661427815681} is an apocalyptic number.

It is an amenable number.

39661427815681 is a deficient number, since it is larger than the sum of its proper divisors (5665918259391).

39661427815681 is an equidigital number, since it uses as much as digits as its factorization.

39661427815681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5665918259390.

The product of its digits is 104509440, while the sum is 67.

The spelling of 39661427815681 in words is "thirty-nine trillion, six hundred sixty-one billion, four hundred twenty-seven million, eight hundred fifteen thousand, six hundred eighty-one".