820656861 has 32 divisors (see below), whose sum is σ = 1192060800. Its totient is φ = 500152320.

The previous prime is 820656853. The next prime is 820656869. The reversal of 820656861 is 168656028.

It is an interprime number because it is at equal distance from previous prime (820656853) and next prime (820656869).

It is not a de Polignac number, because 820656861 - 2³ = 820656853 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820656869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 561750 + ... + 563208.

It is an arithmetic number, because the mean of its divisors is an integer number (37251900).

Almost surely, 2^820656861 is an apocalyptic number.

It is an amenable number.

820656861 is a deficient number, since it is larger than the sum of its proper divisors (371403939).

820656861 is a wasteful number, since it uses less digits than its factorization.

820656861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1789.

The product of its (nonzero) digits is 138240, while the sum is 42.

The square root of 820656861 is about 28647.1091211661. The cubic root of 820656861 is about 936.2400205828.

The spelling of 820656861 in words is "eight hundred twenty million, six hundred fifty-six thousand, eight hundred sixty-one".