21201200000128 has 32 divisors (see below), whose sum is σ = 42302657779020. Its totient is φ = 10584062361600.

The previous prime is 21201200000089. The next prime is 21201200000129. The reversal of 21201200000128 is 82100000210212.

It can be written as a sum of positive squares in 2 ways, for example, as 15127183439424 + 6074016560704 = 3889368^2 + 2464552^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (21201200000129) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 129117933 + ... + 129282028.

Almost surely, 2^{21201200000128} is an apocalyptic number.

It is an amenable number.

21201200000128 is a deficient number, since it is larger than the sum of its proper divisors (21101457778892).

21201200000128 is an equidigital number, since it uses as much as digits as its factorization.

21201200000128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258400616 (or 258400604 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

The spelling of 21201200000128 in words is "twenty-one trillion, two hundred one billion, two hundred million, one hundred twenty-eight", and thus it is an aban number.