212021309 has 4 divisors (see below), whose sum is σ = 212103360. Its totient is φ = 211939260.

The previous prime is 212021239. The next prime is 212021311. The reversal of 212021309 is 903120212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 212021309 - 2¹² = 212017213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212021389) 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, 37019 + ... + 42360.

It is an arithmetic number, because the mean of its divisors is an integer number (53025840).

Almost surely, 2^212021309 is an apocalyptic number.

It is an amenable number.

212021309 is a deficient number, since it is larger than the sum of its proper divisors (82051).

212021309 is an equidigital number, since it uses as much as digits as its factorization.

212021309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82050.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 212021309 is about 14560.9515142383. The cubic root of 212021309 is about 596.2931730697.

The spelling of 212021309 in words is "two hundred twelve million, twenty-one thousand, three hundred nine".