7891681613 has 2 divisors, whose sum is σ = 7891681614. Its totient is φ = 7891681612.

The previous prime is 7891681607. The next prime is 7891681621. The reversal of 7891681613 is 3161861987.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6617334409 + 1274347204 = 81347^2 + 35698^2 .

It is an emirp because it is prime and its reverse (3161861987) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 7891681613 - 2⁶ = 7891681549 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7891681643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3945840806 + 3945840807.

It is an arithmetic number, because the mean of its divisors is an integer number (3945840807).

Almost surely, 2^7891681613 is an apocalyptic number.

It is an amenable number.

7891681613 is a deficient number, since it is larger than the sum of its proper divisors (1).

7891681613 is an equidigital number, since it uses as much as digits as its factorization.

7891681613 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 435456, while the sum is 50.

The square root of 7891681613 is about 88835.1372656113. The cubic root of 7891681613 is about 1990.9324193696.

The spelling of 7891681613 in words is "seven billion, eight hundred ninety-one million, six hundred eighty-one thousand, six hundred thirteen".