642221163791 has 2 divisors, whose sum is σ = 642221163792. Its totient is φ = 642221163790.

The previous prime is 642221163781. The next prime is 642221163799. The reversal of 642221163791 is 197361122246.

642221163791 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 642221163791 - 2¹⁰ = 642221162767 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642221163799) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321110581895 + 321110581896.

It is an arithmetic number, because the mean of its divisors is an integer number (321110581896).

Almost surely, 2^642221163791 is an apocalyptic number.

642221163791 is a deficient number, since it is larger than the sum of its proper divisors (1).

642221163791 is an equidigital number, since it uses as much as digits as its factorization.

642221163791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 217728, while the sum is 44.

The spelling of 642221163791 in words is "six hundred forty-two billion, two hundred twenty-one million, one hundred sixty-three thousand, seven hundred ninety-one".