656743128 has 64 divisors (see below), whose sum is σ = 1691712000. Its totient is φ = 212338560.

The previous prime is 656743123. The next prime is 656743159. The reversal of 656743128 is 821347656.

It is a Cunningham number, because it is equal to 25627²-1.

It is a self number, because there is not a number n which added to its sum of digits gives 656743128.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656743123) 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, 151633 + ... + 155903.

It is an arithmetic number, because the mean of its divisors is an integer number (26433000).

Almost surely, 2^656743128 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 656743128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (845856000).

656743128 is an abundant number, since it is smaller than the sum of its proper divisors (1034968872).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

656743128 is a wasteful number, since it uses less digits than its factorization.

656743128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4472 (or 4468 counting only the distinct ones).

The product of its digits is 241920, while the sum is 42.

The square root of 656743128 is about 25626.9999804893. Note that the first 4 decimals coincide. The cubic root of 656743128 is about 869.2242735259.

The spelling of 656743128 in words is "six hundred fifty-six million, seven hundred forty-three thousand, one hundred twenty-eight".