840909917 has 8 divisors (see below), whose sum is σ = 844640376. Its totient is φ = 837188352.

The previous prime is 840909889. The next prime is 840909919. The reversal of 840909917 is 719909048.

840909917 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 6220036 + 834689881 = 2494^2 + 28891^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-840909917 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 (840909919) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 243233 + ... + 246665.

It is an arithmetic number, because the mean of its divisors is an integer number (105580047).

Almost surely, 2^840909917 is an apocalyptic number.

It is an amenable number.

840909917 is a deficient number, since it is larger than the sum of its proper divisors (3730459).

840909917 is a wasteful number, since it uses less digits than its factorization.

840909917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4447.

The product of its (nonzero) digits is 163296, while the sum is 47.

The square root of 840909917 is about 28998.4468032341. The cubic root of 840909917 is about 943.8793643873.

The spelling of 840909917 in words is "eight hundred forty million, nine hundred nine thousand, nine hundred seventeen".