196666391 has 4 divisors (see below), whose sum is σ = 201240072. Its totient is φ = 192092712.

The previous prime is 196666357. The next prime is 196666409. The reversal of 196666391 is 193666691.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 193666691 = 1627 ⋅119033.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-196666391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (196666991) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2286776 + ... + 2286861.

It is an arithmetic number, because the mean of its divisors is an integer number (50310018).

Almost surely, 2^196666391 is an apocalyptic number.

196666391 is a deficient number, since it is larger than the sum of its proper divisors (4573681).

196666391 is an equidigital number, since it uses as much as digits as its factorization.

196666391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4573680.

The product of its digits is 314928, while the sum is 47.

The square root of 196666391 is about 14023.7794834346. The cubic root of 196666391 is about 581.5361488351.

The spelling of 196666391 in words is "one hundred ninety-six million, six hundred sixty-six thousand, three hundred ninety-one".