211221011 has 4 divisors (see below), whose sum is σ = 218034624. Its totient is φ = 204407400.

The previous prime is 211220993. The next prime is 211221013. The reversal of 211221011 is 110122112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-211221011 is a prime.

It is a super-2 number, since 2×211221011² = 89228630975724242, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 211220983 and 211221001.

It is not an unprimeable number, because it can be changed into a prime (211221013) 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, 3406760 + ... + 3406821.

It is an arithmetic number, because the mean of its divisors is an integer number (54508656).

Almost surely, 2^211221011 is an apocalyptic number.

211221011 is a deficient number, since it is larger than the sum of its proper divisors (6813613).

211221011 is an equidigital number, since it uses as much as digits as its factorization.

211221011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6813612.

The product of its (nonzero) digits is 8, while the sum is 11.

The square root of 211221011 is about 14533.4445676171. Note that the first 3 decimals coincide. The cubic root of 211221011 is about 595.5419688180.

Adding to 211221011 its reverse (110122112), we get a palindrome (321343123).

The spelling of 211221011 in words is "two hundred eleven million, two hundred twenty-one thousand, eleven".