656857209841 has 16 divisors (see below), whose sum is σ = 765162062208. Its totient is φ = 552221683200.

The previous prime is 656857209839. The next prime is 656857209857. The reversal of 656857209841 is 148902758656.

It is a cyclic number.

It is not a de Polignac number, because 656857209841 - 2¹ = 656857209839 is a prime.

It is a super-2 number, since 2×656857209841² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (61).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 656857209841.

It is not an unprimeable number, because it can be changed into a prime (656857809841) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2028175 + ... + 2329636.

It is an arithmetic number, because the mean of its divisors is an integer number (47822628888).

Almost surely, 2^656857209841 is an apocalyptic number.

656857209841 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

656857209841 is a deficient number, since it is larger than the sum of its proper divisors (108304852367).

656857209841 is a wasteful number, since it uses less digits than its factorization.

656857209841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4358232.

The product of its (nonzero) digits is 29030400, while the sum is 61.

The spelling of 656857209841 in words is "six hundred fifty-six billion, eight hundred fifty-seven million, two hundred nine thousand, eight hundred forty-one".