642936191 has 2 divisors, whose sum is σ = 642936192. Its totient is φ = 642936190.

The previous prime is 642936167. The next prime is 642936199. The reversal of 642936191 is 191639246.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 642936191 - 2⁶ = 642936127 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642936199) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321468095 + 321468096.

It is an arithmetic number, because the mean of its divisors is an integer number (321468096).

Almost surely, 2^642936191 is an apocalyptic number.

642936191 is a deficient number, since it is larger than the sum of its proper divisors (1).

642936191 is an equidigital number, since it uses as much as digits as its factorization.

642936191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 69984, while the sum is 41.

The square root of 642936191 is about 25356.1864443374. The cubic root of 642936191 is about 863.0897473561.

The spelling of 642936191 in words is "six hundred forty-two million, nine hundred thirty-six thousand, one hundred ninety-one".