211812557209 has 4 divisors (see below), whose sum is σ = 231068244240. Its totient is φ = 192556870180.

The previous prime is 211812557113. The next prime is 211812557249. The reversal of 211812557209 is 902755218112.

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 211812557209 - 2²⁵ = 211779002777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (211812557249) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9627843499 + ... + 9627843520.

It is an arithmetic number, because the mean of its divisors is an integer number (57767061060).

Almost surely, 2^211812557209 is an apocalyptic number.

It is an amenable number.

211812557209 is a deficient number, since it is larger than the sum of its proper divisors (19255687031).

211812557209 is a wasteful number, since it uses less digits than its factorization.

211812557209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19255687030.

The product of its (nonzero) digits is 100800, while the sum is 43.

The spelling of 211812557209 in words is "two hundred eleven billion, eight hundred twelve million, five hundred fifty-seven thousand, two hundred nine".