191881643 has 2 divisors, whose sum is σ = 191881644. Its totient is φ = 191881642.

The previous prime is 191881639. The next prime is 191881699. The reversal of 191881643 is 346188191.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 191881643 - 2² = 191881639 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 191881643.

It is not a weakly prime, because it can be changed into another prime (191881043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95940821 + 95940822.

It is an arithmetic number, because the mean of its divisors is an integer number (95940822).

Almost surely, 2^191881643 is an apocalyptic number.

191881643 is a deficient number, since it is larger than the sum of its proper divisors (1).

191881643 is an equidigital number, since it uses as much as digits as its factorization.

191881643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 41.

The square root of 191881643 is about 13852.1349618028. The cubic root of 191881643 is about 576.7812618590.

The spelling of 191881643 in words is "one hundred ninety-one million, eight hundred eighty-one thousand, six hundred forty-three".