1643043191 has 2 divisors, whose sum is σ = 1643043192. Its totient is φ = 1643043190.

The previous prime is 1643043137. The next prime is 1643043197. The reversal of 1643043191 is 1913403461.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1643043191 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1643043197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 821521595 + 821521596.

It is an arithmetic number, because the mean of its divisors is an integer number (821521596).

Almost surely, 2^1643043191 is an apocalyptic number.

1643043191 is a deficient number, since it is larger than the sum of its proper divisors (1).

1643043191 is an equidigital number, since it uses as much as digits as its factorization.

1643043191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 1643043191 is about 40534.4691713115. The cubic root of 1643043191 is about 1180.0026790612.

The spelling of 1643043191 in words is "one billion, six hundred forty-three million, forty-three thousand, one hundred ninety-one".