2128171680 has 72 divisors (see below), whose sum is σ = 7262390772. Its totient is φ = 567512064.

The previous prime is 2128171667. The next prime is 2128171687. The reversal of 2128171680 is 861718212.

It can be written as a sum of positive squares in 2 ways, for example, as 2102405904 + 25765776 = 45852^2 + 5076^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×2128171680² = 9058229399108044800, which contains 22 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (2128171687) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 737509 + ... + 740388.

Almost surely, 2^2128171680 is an apocalyptic number.

2128171680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2128171680 is an abundant number, since it is smaller than the sum of its proper divisors (5134219092).

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

2128171680 is a wasteful number, since it uses less digits than its factorization.

2128171680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1477918 (or 1477907 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The square root of 2128171680 is about 46132.1111591481. Note that the first 4 decimals coincide. The cubic root of 2128171680 is about 1286.2801073568.

Adding to 2128171680 its reverse (861718212), we get a palindrome (2989889892).

The spelling of 2128171680 in words is "two billion, one hundred twenty-eight million, one hundred seventy-one thousand, six hundred eighty".