51205645656 has 192 divisors, whose sum is σ = 154087989120. Its totient is φ = 15231490560.

The previous prime is 51205645649. The next prime is 51205645697. The reversal of 51205645656 is 65654650215.

51205645656 is a `hidden beast` number, since 5 + 1 + 20 + 5 + 64 + 565 + 6 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 16607491 + ... + 16610573.

It is an arithmetic number, because the mean of its divisors is an integer number (802541610).

Almost surely, 2^51205645656 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 51205645656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77043994560).

51205645656 is an abundant number, since it is smaller than the sum of its proper divisors (102882343464).

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

51205645656 is a wasteful number, since it uses less digits than its factorization.

51205645656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3486 (or 3479 counting only the distinct ones).

The product of its (nonzero) digits is 1080000, while the sum is 45.

The spelling of 51205645656 in words is "fifty-one billion, two hundred five million, six hundred forty-five thousand, six hundred fifty-six".