2161378656 has 36 divisors (see below), whose sum is σ = 6146421372. Its totient is φ = 720459456.

The previous prime is 2161378633. The next prime is 2161378669. The reversal of 2161378656 is 6568731612.

2161378656 is a `hidden beast` number, since 21 + 613 + 7 + 8 + 6 + 5 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×2161378656² = 9343115389224732672, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3752106 + ... + 3752681.

It is an arithmetic number, because the mean of its divisors is an integer number (170733927).

Almost surely, 2^2161378656 is an apocalyptic number.

It is an amenable number.

2161378656 is an abundant number, since it is smaller than the sum of its proper divisors (3985042716).

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

2161378656 is a wasteful number, since it uses less digits than its factorization.

2161378656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7504803 (or 7504792 counting only the distinct ones).

The product of its digits is 362880, while the sum is 45.

The square root of 2161378656 is about 46490.6297655775. The cubic root of 2161378656 is about 1292.9357762973.

The spelling of 2161378656 in words is "two billion, one hundred sixty-one million, three hundred seventy-eight thousand, six hundred fifty-six".