1642966778891 has 2 divisors, whose sum is σ = 1642966778892. Its totient is φ = 1642966778890.

The previous prime is 1642966778867. The next prime is 1642966778909. The reversal of 1642966778891 is 1988776692461.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1642966778891 is a prime.

It is not a weakly prime, because it can be changed into another prime (1642966771891) 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, 821483389445 + 821483389446.

It is an arithmetic number, because the mean of its divisors is an integer number (821483389446).

Almost surely, 2^{1642966778891} is an apocalyptic number.

1642966778891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1642966778891 is an equidigital number, since it uses as much as digits as its factorization.

1642966778891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 438939648, while the sum is 74.

The spelling of 1642966778891 in words is "one trillion, six hundred forty-two billion, nine hundred sixty-six million, seven hundred seventy-eight thousand, eight hundred ninety-one".