2121956784 has 160 divisors (see below), whose sum is σ = 6437088000. Its totient is φ = 667408896.

The previous prime is 2121956783. The next prime is 2121956801. The reversal of 2121956784 is 4876591212.

2121956784 is a `hidden beast` number, since 2 + 1 + 2 + 1 + 9 + 567 + 84 = 666.

It is not an unprimeable number, because it can be changed into a prime (2121956783) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3438844 + ... + 3439460.

It is an arithmetic number, because the mean of its divisors is an integer number (40231800).

Almost surely, 2^2121956784 is an apocalyptic number.

2121956784 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2121956784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3218544000).

2121956784 is an abundant number, since it is smaller than the sum of its proper divisors (4315131216).

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

2121956784 is a wasteful number, since it uses less digits than its factorization.

2121956784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1072 (or 1060 counting only the distinct ones).

The product of its digits is 241920, while the sum is 45.

The square root of 2121956784 is about 46064.7021481741. The cubic root of 2121956784 is about 1285.0267793578.

The spelling of 2121956784 in words is "two billion, one hundred twenty-one million, nine hundred fifty-six thousand, seven hundred eighty-four".