856377661 has 2 divisors, whose sum is σ = 856377662. Its totient is φ = 856377660.

The previous prime is 856377623. The next prime is 856377667. The reversal of 856377661 is 166773658.

856377661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 590198436 + 266179225 = 24294^2 + 16315^2 .

It is a cyclic number.

It is not a de Polignac number, because 856377661 - 2⁹ = 856377149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (856377667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428188830 + 428188831.

It is an arithmetic number, because the mean of its divisors is an integer number (428188831).

Almost surely, 2^856377661 is an apocalyptic number.

It is an amenable number.

856377661 is a deficient number, since it is larger than the sum of its proper divisors (1).

856377661 is an equidigital number, since it uses as much as digits as its factorization.

856377661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1270080, while the sum is 49.

The square root of 856377661 is about 29263.9310585574. The cubic root of 856377661 is about 949.6314954876.

The spelling of 856377661 in words is "eight hundred fifty-six million, three hundred seventy-seven thousand, six hundred sixty-one".