840606661 has 4 divisors (see below), whose sum is σ = 848045772. Its totient is φ = 833167552.

The previous prime is 840606643. The next prime is 840606677. The reversal of 840606661 is 166606048.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 448804225 + 391802436 = 21185^2 + 19794^2 .

It is a cyclic number.

It is not a de Polignac number, because 840606661 - 2⁵ = 840606629 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 840606661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (840606061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3719386 + ... + 3719611.

It is an arithmetic number, because the mean of its divisors is an integer number (212011443).

Almost surely, 2^840606661 is an apocalyptic number.

It is an amenable number.

840606661 is a deficient number, since it is larger than the sum of its proper divisors (7439111).

840606661 is a wasteful number, since it uses less digits than its factorization.

840606661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7439110.

The product of its (nonzero) digits is 41472, while the sum is 37.

The square root of 840606661 is about 28993.2174999602. The cubic root of 840606661 is about 943.7658875094.

The spelling of 840606661 in words is "eight hundred forty million, six hundred six thousand, six hundred sixty-one".