211220309 has 16 divisors (see below), whose sum is σ = 221907840. Its totient is φ = 200854080.

The previous prime is 211220281. The next prime is 211220351. The reversal of 211220309 is 903022112.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-211220309 is a prime.

It is a super-2 number, since 2×211220309² = 89228037868110962, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211220389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 334424 + ... + 335054.

It is an arithmetic number, because the mean of its divisors is an integer number (13869240).

Almost surely, 2^211220309 is an apocalyptic number.

It is an amenable number.

211220309 is a deficient number, since it is larger than the sum of its proper divisors (10687531).

211220309 is a wasteful number, since it uses less digits than its factorization.

211220309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 860.

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

The square root of 211220309 is about 14533.4204164058. The cubic root of 211220309 is about 595.5413090495.

The spelling of 211220309 in words is "two hundred eleven million, two hundred twenty thousand, three hundred nine".