857646661 has 4 divisors (see below), whose sum is σ = 857705824. Its totient is φ = 857587500.

The previous prime is 857646637. The next prime is 857646677. The reversal of 857646661 is 166646758.

857646661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 857646661 - 2¹⁵ = 857613893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (857646611) 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, 8536 + ... + 42286.

It is an arithmetic number, because the mean of its divisors is an integer number (214426456).

Almost surely, 2^857646661 is an apocalyptic number.

It is an amenable number.

857646661 is a deficient number, since it is larger than the sum of its proper divisors (59163).

857646661 is a wasteful number, since it uses less digits than its factorization.

857646661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59162.

The product of its digits is 1451520, while the sum is 49.

The square root of 857646661 is about 29285.6050133850. The cubic root of 857646661 is about 950.1003258774.

The spelling of 857646661 in words is "eight hundred fifty-seven million, six hundred forty-six thousand, six hundred sixty-one".