840542861 has 2 divisors, whose sum is σ = 840542862. Its totient is φ = 840542860.

The previous prime is 840542837. The next prime is 840542891. The reversal of 840542861 is 168245048.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 421521961 + 419020900 = 20531^2 + 20470^2 .

It is a cyclic number.

It is not a de Polignac number, because 840542861 - 2¹⁸ = 840280717 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (840542831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420271430 + 420271431.

It is an arithmetic number, because the mean of its divisors is an integer number (420271431).

Almost surely, 2^840542861 is an apocalyptic number.

It is an amenable number.

840542861 is a deficient number, since it is larger than the sum of its proper divisors (1).

840542861 is an equidigital number, since it uses as much as digits as its factorization.

840542861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 61440, while the sum is 38.

The square root of 840542861 is about 28992.1172217553. The cubic root of 840542861 is about 943.7420103939.

The spelling of 840542861 in words is "eight hundred forty million, five hundred forty-two thousand, eight hundred sixty-one".