211110021 has 6 divisors (see below), whose sum is σ = 304936710.
Its totient is φ = 140740008.
The previous prime is 211110017. The next prime is 211110061. The reversal of 211110021 is 120011112.
It is a happy number.
It can be written as a sum of positive squares in only one way, i.e., 143640225 + 67469796 = 11985^2 + 8214^2
It is not a de Polignac number, because 211110021 - 22 = 211110017 is a prime.
It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 23456669 = 211110021 / (2 + 1 + 1 + 1 + 1 + 0 + 0 + 2 + 1).
It is a junction number, because it is equal to n+sod(n) for n = 211109985 and 211110012.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (211110061) 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 5 ways as a sum of consecutive naturals, for example, 11728326 + ... + 11728343.
It is an arithmetic number, because the mean of its divisors is an integer number (50822785).
Almost surely, 2211110021 is an apocalyptic number.
It is an amenable number.
211110021 is a deficient number, since it is larger than the sum of its proper divisors (93826689).
211110021 is a wasteful number, since it uses less digits than its factorization.
211110021 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 23456675 (or 23456672 counting only the distinct ones).
The product of its (nonzero) digits is 4, while the sum is 9.
The square root of 211110021 is about 14529.6256317911.
The cubic root of 211110021 is about 595.4376376818.
Adding to 211110021 its reverse (120011112), we get a palindrome (331121133).
The spelling of 211110021 in words is "two hundred eleven million, one hundred ten thousand, twenty-one".