1939664891 has 2 divisors, whose sum is σ = 1939664892. Its totient is φ = 1939664890.

The previous prime is 1939664887. The next prime is 1939664893. The reversal of 1939664891 is 1984669391.

It is a strong prime.

It is an emirp because it is prime and its reverse (1984669391) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1939664891 - 2² = 1939664887 is a prime.

Together with 1939664893, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1939664893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 969832445 + 969832446.

It is an arithmetic number, because the mean of its divisors is an integer number (969832446).

Almost surely, 2^1939664891 is an apocalyptic number.

1939664891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1939664891 is an equidigital number, since it uses as much as digits as its factorization.

1939664891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2519424, while the sum is 56.

The square root of 1939664891 is about 44041.6267978375. The cubic root of 1939664891 is about 1247.1218883447.

The spelling of 1939664891 in words is "one billion, nine hundred thirty-nine million, six hundred sixty-four thousand, eight hundred ninety-one".