7987447891 has 2 divisors, whose sum is σ = 7987447892. Its totient is φ = 7987447890.

The previous prime is 7987447877. The next prime is 7987447903. The reversal of 7987447891 is 1987447897.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 7987447891 - 2²⁵ = 7953893459 is a prime.

It is a super-2 number, since 2×7987447891² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (7987442891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3993723945 + 3993723946.

It is an arithmetic number, because the mean of its divisors is an integer number (3993723946).

Almost surely, 2^7987447891 is an apocalyptic number.

7987447891 is a deficient number, since it is larger than the sum of its proper divisors (1).

7987447891 is an equidigital number, since it uses as much as digits as its factorization.

7987447891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28449792, while the sum is 64.

The square root of 7987447891 is about 89372.5231321126. The cubic root of 7987447891 is about 1998.9534433718.

It can be divided in two parts, 79874 and 47891, that added together give a triangular number (127765 = T₅₀₅).

The spelling of 7987447891 in words is "seven billion, nine hundred eighty-seven million, four hundred forty-seven thousand, eight hundred ninety-one".