840782081 has 2 divisors, whose sum is σ = 840782082. Its totient is φ = 840782080.

The previous prime is 840782057. The next prime is 840782087. The reversal of 840782081 is 180287048.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 794337856 + 46444225 = 28184^2 + 6815^2 .

It is a cyclic number.

It is not a de Polignac number, because 840782081 - 2²² = 836587777 is a prime.

It is a super-3 number, since 3×840782081³ (a number of 28 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (840782087) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420391040 + 420391041.

It is an arithmetic number, because the mean of its divisors is an integer number (420391041).

Almost surely, 2^840782081 is an apocalyptic number.

It is an amenable number.

840782081 is a deficient number, since it is larger than the sum of its proper divisors (1).

840782081 is an equidigital number, since it uses as much as digits as its factorization.

840782081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28672, while the sum is 38.

The square root of 840782081 is about 28996.2425324386. The cubic root of 840782081 is about 943.8315321225.

The spelling of 840782081 in words is "eight hundred forty million, seven hundred eighty-two thousand, eighty-one".