212021009 has 4 divisors (see below), whose sum is σ = 213546480. Its totient is φ = 210495540.

The previous prime is 212020987. The next prime is 212021021. The reversal of 212021009 is 900120212.

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 a de Polignac number, because none of the positive numbers 2^k-212021009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (212021099) 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, 762527 + ... + 762804.

It is an arithmetic number, because the mean of its divisors is an integer number (53386620).

Almost surely, 2^212021009 is an apocalyptic number.

It is an amenable number.

212021009 is a deficient number, since it is larger than the sum of its proper divisors (1525471).

212021009 is a wasteful number, since it uses less digits than its factorization.

212021009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1525470.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 212021009 is about 14560.9412127101. The cubic root of 212021009 is about 596.2928918275.

The spelling of 212021009 in words is "two hundred twelve million, twenty-one thousand, nine".