212171920 has 20 divisors (see below), whose sum is σ = 493299900. Its totient is φ = 84868736.

The previous prime is 212171909. The next prime is 212171929. The reversal of 212171920 is 29171212.

It can be written as a sum of positive squares in 2 ways, for example, as 148937616 + 63234304 = 12204^2 + 7952^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is not an unprimeable number, because it can be changed into a prime (212171929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1325995 + ... + 1326154.

It is an arithmetic number, because the mean of its divisors is an integer number (24664995).

Almost surely, 2^212171920 is an apocalyptic number.

212171920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

212171920 is an abundant number, since it is smaller than the sum of its proper divisors (281127980).

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

212171920 is a wasteful number, since it uses less digits than its factorization.

212171920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2652162 (or 2652156 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 25.

The square root of 212171920 is about 14566.1223391814. The cubic root of 212171920 is about 596.4343334945.

The spelling of 212171920 in words is "two hundred twelve million, one hundred seventy-one thousand, nine hundred twenty".