1986947891 has 2 divisors, whose sum is σ = 1986947892. Its totient is φ = 1986947890.

The previous prime is 1986947849. The next prime is 1986947917. The reversal of 1986947891 is 1987496891.

It is a strong prime.

It is an emirp because it is prime and its reverse (1987496891) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1986947891 is a prime.

It is not a weakly prime, because it can be changed into another prime (1986947191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 993473945 + 993473946.

It is an arithmetic number, because the mean of its divisors is an integer number (993473946).

Almost surely, 2^1986947891 is an apocalyptic number.

1986947891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1986947891 is an equidigital number, since it uses as much as digits as its factorization.

1986947891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7838208, while the sum is 62.

The square root of 1986947891 is about 44575.1936731631. The cubic root of 1986947891 is about 1257.1742948977.

The spelling of 1986947891 in words is "one billion, nine hundred eighty-six million, nine hundred forty-seven thousand, eight hundred ninety-one".