656811438844861 has 16 divisors (see below), whose sum is σ = 667714850822448. Its totient is φ = 645912426816000.

The previous prime is 656811438844837. The next prime is 656811438844867. The reversal of 656811438844861 is 168448834118656.

It can be written as a sum of positive squares in 8 ways, for example, as 283926881016900 + 372884557827961 = 16850130^2 + 19310219^2 .

It is a cyclic number.

It is not a de Polignac number, because 656811438844861 - 2¹⁷ = 656811438713789 is a prime.

It is a super-2 number, since 2×656811438844861² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656811438844867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8468718895 + ... + 8468796451.

It is an arithmetic number, because the mean of its divisors is an integer number (41732178176403).

Almost surely, 2^{656811438844861} is an apocalyptic number.

656811438844861 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

656811438844861 is a deficient number, since it is larger than the sum of its proper divisors (10903411977587).

656811438844861 is a wasteful number, since it uses less digits than its factorization.

656811438844861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104112.

The product of its digits is 849346560, while the sum is 73.

The spelling of 656811438844861 in words is "six hundred fifty-six trillion, eight hundred eleven billion, four hundred thirty-eight million, eight hundred forty-four thousand, eight hundred sixty-one".