2161987728 has 80 divisors (see below), whose sum is σ = 5733716352. Its totient is φ = 701568000.

The previous prime is 2161987679. The next prime is 2161987753. The reversal of 2161987728 is 8277891612.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1240938 + ... + 1242678.

Almost surely, 2^2161987728 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 2161987728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2866858176).

2161987728 is an abundant number, since it is smaller than the sum of its proper divisors (3571728624).

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

2161987728 is a wasteful number, since it uses less digits than its factorization.

2161987728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2424 (or 2418 counting only the distinct ones).

The product of its digits is 677376, while the sum is 51.

The square root of 2161987728 is about 46497.1797854451. The cubic root of 2161987728 is about 1293.0572137600.

The spelling of 2161987728 in words is "two billion, one hundred sixty-one million, nine hundred eighty-seven thousand, seven hundred twenty-eight".