211000021 has 2 divisors, whose sum is σ = 211000022. Its totient is φ = 211000020.

The previous prime is 211000007. The next prime is 211000033. The reversal of 211000021 is 120000112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 147622500 + 63377521 = 12150^2 + 7961^2 .

It is a cyclic number.

It is not a de Polignac number, because 211000021 - 2¹¹ = 210997973 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 210999968 and 211000013.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211000051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105500010 + 105500011.

It is an arithmetic number, because the mean of its divisors is an integer number (105500011).

Almost surely, 2^211000021 is an apocalyptic number.

It is an amenable number.

211000021 is a deficient number, since it is larger than the sum of its proper divisors (1).

211000021 is an equidigital number, since it uses as much as digits as its factorization.

211000021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 211000021 is about 14525.8397691837. The cubic root of 211000021 is about 595.3342010643.

Adding to 211000021 its reverse (120000112), we get a palindrome (331000133).

Subtracting from 211000021 its reverse (120000112), we obtain a palindrome (90999909).

The spelling of 211000021 in words is "two hundred eleven million, twenty-one", and thus it is an aban number.