21020521671172 has 24 divisors (see below), whose sum is σ = 38105064466560. Its totient is φ = 10134325572000.

The previous prime is 21020521671167. The next prime is 21020521671179. The reversal of 21020521671172 is 27117612502012.

It is not an unprimeable number, because it can be changed into a prime (21020521671179) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 120559618 + ... + 120733849.

It is an arithmetic number, because the mean of its divisors is an integer number (1587711019440).

Almost surely, 2^{21020521671172} is an apocalyptic number.

It is an amenable number.

21020521671172 is a deficient number, since it is larger than the sum of its proper divisors (17084542795388).

21020521671172 is a wasteful number, since it uses less digits than its factorization.

21020521671172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 241294251 (or 241294249 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 37.

The spelling of 21020521671172 in words is "twenty-one trillion, twenty billion, five hundred twenty-one million, six hundred seventy-one thousand, one hundred seventy-two".