212509 has 4 divisors (see below), whose sum is σ = 231840. Its totient is φ = 193180.

The previous prime is 212507. The next prime is 212557. The reversal of 212509 is 905212.

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 212509 - 2¹ = 212507 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

212509 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9649 + ... + 9670.

It is an arithmetic number, because the mean of its divisors is an integer number (57960).

2²¹²⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

212509 is a deficient number, since it is larger than the sum of its proper divisors (19331).

212509 is a wasteful number, since it uses less digits than its factorization.

212509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19330.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 212509 is about 460.9869846319. The cubic root of 212509 is about 59.6750020432.

The spelling of 212509 in words is "two hundred twelve thousand, five hundred nine".