856041661 has 4 divisors (see below), whose sum is σ = 856291900. Its totient is φ = 855791424.

The previous prime is 856041653. The next prime is 856041673. The reversal of 856041661 is 166140658.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 166140658 = 2 ⋅83070329.

It can be written as a sum of positive squares in 2 ways, for example, as 195860025 + 660181636 = 13995^2 + 25694^2 .

It is a cyclic number.

It is not a de Polignac number, because 856041661 - 2³ = 856041653 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 856041661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (856041601) 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, 119916 + ... + 126853.

It is an arithmetic number, because the mean of its divisors is an integer number (214072975).

Almost surely, 2^856041661 is an apocalyptic number.

It is an amenable number.

856041661 is a deficient number, since it is larger than the sum of its proper divisors (250239).

856041661 is a wasteful number, since it uses less digits than its factorization.

856041661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 250238.

The product of its (nonzero) digits is 34560, while the sum is 37.

The square root of 856041661 is about 29258.1896398256. The cubic root of 856041661 is about 949.5072831858.

The spelling of 856041661 in words is "eight hundred fifty-six million, forty-one thousand, six hundred sixty-one".