212111561 has 4 divisors (see below), whose sum is σ = 217044432. Its totient is φ = 207178692.

The previous prime is 212111551. The next prime is 212111569. The reversal of 212111561 is 165111212.

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-212111561 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (212111569) 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, 2466371 + ... + 2466456.

It is an arithmetic number, because the mean of its divisors is an integer number (54261108).

Almost surely, 2^212111561 is an apocalyptic number.

It is an amenable number.

212111561 is a deficient number, since it is larger than the sum of its proper divisors (4932871).

212111561 is an equidigital number, since it uses as much as digits as its factorization.

212111561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4932870.

The product of its digits is 120, while the sum is 20.

The square root of 212111561 is about 14564.0502951617. The cubic root of 212111561 is about 596.3777699394.

Adding to 212111561 its reverse (165111212), we get a palindrome (377222773).

The spelling of 212111561 in words is "two hundred twelve million, one hundred eleven thousand, five hundred sixty-one".