211009806 has 64 divisors (see below), whose sum is σ = 541301760. Its totient is φ = 59680800.

The previous prime is 211009781. The next prime is 211009811. The reversal of 211009806 is 608900112.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 211009806.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 35415 + ... + 40941.

It is an arithmetic number, because the mean of its divisors is an integer number (8457840).

Almost surely, 2^211009806 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 211009806, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (270650880).

211009806 is an abundant number, since it is smaller than the sum of its proper divisors (330291954).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

211009806 is a wasteful number, since it uses less digits than its factorization.

211009806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5646 (or 5640 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 211009806 is about 14526.1765788524. The cubic root of 211009806 is about 595.3434036781.

Adding to 211009806 its reverse (608900112), we get a palindrome (819909918).

The spelling of 211009806 in words is "two hundred eleven million, nine thousand, eight hundred six".