2161757638656 has 1664 divisors, whose sum is σ = 8696247091200. Its totient is φ = 513589248000.

The previous prime is 2161757638639. The next prime is 2161757638681. The reversal of 2161757638656 is 6568367571612.

2161757638656 is a `hidden beast` number, since 2 + 1 + 6 + 1 + 7 + 576 + 3 + 8 + 6 + 56 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

Its product of digits (76204800) is a multiple of the sum of its prime divisors (504).

It is a junction number, because it is equal to n+sod(n) for n = 2161757638593 and 2161757638602.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 5015678761 + ... + 5015679191.

Almost surely, 2^{2161757638656} 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 2161757638656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4348123545600).

2161757638656 is an abundant number, since it is smaller than the sum of its proper divisors (6534489452544).

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

2161757638656 is a wasteful number, since it uses less digits than its factorization.

2161757638656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 532 (or 504 counting only the distinct ones).

The product of its digits is 76204800, while the sum is 63.

The spelling of 2161757638656 in words is "two trillion, one hundred sixty-one billion, seven hundred fifty-seven million, six hundred thirty-eight thousand, six hundred fifty-six".