840157891 has 2 divisors, whose sum is σ = 840157892. Its totient is φ = 840157890.

The previous prime is 840157861. The next prime is 840157931. The reversal of 840157891 is 198751048.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 840157891 - 2⁷ = 840157763 is a prime.

It is not a weakly prime, because it can be changed into another prime (840157841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420078945 + 420078946.

It is an arithmetic number, because the mean of its divisors is an integer number (420078946).

Almost surely, 2^840157891 is an apocalyptic number.

840157891 is a deficient number, since it is larger than the sum of its proper divisors (1).

840157891 is an equidigital number, since it uses as much as digits as its factorization.

840157891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 80640, while the sum is 43.

The square root of 840157891 is about 28985.4772429229. The cubic root of 840157891 is about 943.5979099327.

The spelling of 840157891 in words is "eight hundred forty million, one hundred fifty-seven thousand, eight hundred ninety-one".