21128332172 has 12 divisors (see below), whose sum is σ = 37035499200. Its totient is φ = 10546760976.

The previous prime is 21128332117. The next prime is 21128332189. The reversal of 21128332172 is 27123382112.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4348547 + ... + 4353402.

It is an arithmetic number, because the mean of its divisors is an integer number (3086291600).

Almost surely, 2^21128332172 is an apocalyptic number.

It is an amenable number.

21128332172 is a deficient number, since it is larger than the sum of its proper divisors (15907167028).

21128332172 is a wasteful number, since it uses less digits than its factorization.

21128332172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8702560 (or 8702558 counting only the distinct ones).

The product of its digits is 8064, while the sum is 32.

The spelling of 21128332172 in words is "twenty-one billion, one hundred twenty-eight million, three hundred thirty-two thousand, one hundred seventy-two".