840197905 has 4 divisors (see below), whose sum is σ = 1008237492. Its totient is φ = 672158320.

The previous prime is 840197893. The next prime is 840197909. The reversal of 840197905 is 509791048.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 457917201 + 382280704 = 21399^2 + 19552^2 .

It is not a de Polignac number, because 840197905 - 2⁵ = 840197873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (840197909) 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, 84019786 + ... + 84019795.

It is an arithmetic number, because the mean of its divisors is an integer number (252059373).

Almost surely, 2^840197905 is an apocalyptic number.

It is an amenable number.

840197905 is a deficient number, since it is larger than the sum of its proper divisors (168039587).

840197905 is a wasteful number, since it uses less digits than its factorization.

840197905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168039586.

The product of its (nonzero) digits is 90720, while the sum is 43.

The square root of 840197905 is about 28986.1674769191. The cubic root of 840197905 is about 943.6128898660.

The spelling of 840197905 in words is "eight hundred forty million, one hundred ninety-seven thousand, nine hundred five".