211111001221 has 4 divisors (see below), whose sum is σ = 211112758944. Its totient is φ = 211109243500.

The previous prime is 211111001219. The next prime is 211111001239. The reversal of 211111001221 is 122100111112.

It is a happy number.

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 211111001221 - 2¹ = 211111001219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211111001261) 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 3 ways as a sum of consecutive naturals, for example, 684355 + ... + 943696.

It is an arithmetic number, because the mean of its divisors is an integer number (52778189736).

Almost surely, 2^211111001221 is an apocalyptic number.

It is an amenable number.

211111001221 is a deficient number, since it is larger than the sum of its proper divisors (1757723).

211111001221 is a wasteful number, since it uses less digits than its factorization.

211111001221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1757722.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 211111001221 its reverse (122100111112), we get a palindrome (333211112333).

The spelling of 211111001221 in words is "two hundred eleven billion, one hundred eleven million, one thousand, two hundred twenty-one".