856005661 has 8 divisors (see below), whose sum is σ = 980524160. Its totient is φ = 732045168.

The previous prime is 856005659. The next prime is 856005679. The reversal of 856005661 is 166500658.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 856005661 - 2¹ = 856005659 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 856005661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (856003661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 136206 + ... + 142351.

It is an arithmetic number, because the mean of its divisors is an integer number (122565520).

Almost surely, 2^856005661 is an apocalyptic number.

It is an amenable number.

856005661 is a deficient number, since it is larger than the sum of its proper divisors (124518499).

856005661 is a wasteful number, since it uses less digits than its factorization.

856005661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279003.

The product of its (nonzero) digits is 43200, while the sum is 37.

The square root of 856005661 is about 29257.5744209940. The cubic root of 856005661 is about 949.4939727972.

The spelling of 856005661 in words is "eight hundred fifty-six million, five thousand, six hundred sixty-one".