840661 has 2 divisors, whose sum is σ = 840662. Its totient is φ = 840660.

The previous prime is 840643. The next prime is 840683. The reversal of 840661 is 166048.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 498436 + 342225 = 706^2 + 585^2 .

It is a cyclic number.

It is not a de Polignac number, because 840661 - 2⁹ = 840149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (840601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420330 + 420331.

It is an arithmetic number, because the mean of its divisors is an integer number (420331).

2⁸⁴⁰⁶⁶¹ is an apocalyptic number.

It is an amenable number.

840661 is a deficient number, since it is larger than the sum of its proper divisors (1).

840661 is an equidigital number, since it uses as much as digits as its factorization.

840661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 840661 is about 916.8756731422. The cubic root of 840661 is about 94.3786222898.

The spelling of 840661 in words is "eight hundred forty thousand, six hundred sixty-one".