840706561 has 2 divisors, whose sum is σ = 840706562. Its totient is φ = 840706560.

The previous prime is 840706541. The next prime is 840706571. The reversal of 840706561 is 165607048.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 637815025 + 202891536 = 25255^2 + 14244^2 .

It is a cyclic number.

It is not a de Polignac number, because 840706561 - 2²³ = 832317953 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 840706561.

It is not a weakly prime, because it can be changed into another prime (840706541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420353280 + 420353281.

It is an arithmetic number, because the mean of its divisors is an integer number (420353281).

Almost surely, 2^840706561 is an apocalyptic number.

It is an amenable number.

840706561 is a deficient number, since it is larger than the sum of its proper divisors (1).

840706561 is an equidigital number, since it uses as much as digits as its factorization.

840706561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40320, while the sum is 37.

The square root of 840706561 is about 28994.9402655015. The cubic root of 840706561 is about 943.8032726035.

The spelling of 840706561 in words is "eight hundred forty million, seven hundred six thousand, five hundred sixty-one".