2121605784 has 112 divisors (see below), whose sum is σ = 6011980920. Its totient is φ = 701550720.

The previous prime is 2121605777. The next prime is 2121605821. The reversal of 2121605784 is 4875061212.

2121605784 is a `hidden beast` number, since 2 + 1 + 21 + 60 + 578 + 4 = 666.

It is a super-2 number, since 2×2121605784² = 9002422205404509312, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 762604 + ... + 765380.

Almost surely, 2^2121605784 is an apocalyptic number.

2121605784 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 2121605784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3005990460).

2121605784 is an abundant number, since it is smaller than the sum of its proper divisors (3890375136).

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

2121605784 is a wasteful number, since it uses less digits than its factorization.

2121605784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2932 (or 2913 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 36.

The square root of 2121605784 is about 46060.8921320462. The cubic root of 2121605784 is about 1284.9559219186.

Adding to 2121605784 its reverse (4875061212), we get a palindrome (6996666996).

The spelling of 2121605784 in words is "two billion, one hundred twenty-one million, six hundred five thousand, seven hundred eighty-four".