211805121 has 16 divisors (see below), whose sum is σ = 308583360. Its totient is φ = 128157120.

The previous prime is 211805117. The next prime is 211805161. The reversal of 211805121 is 121508112.

It is not a de Polignac number, because 211805121 - 2² = 211805117 is a prime.

It is a super-2 number, since 2×211805121² = 89722818563649282, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (211805101) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16635 + ... + 26463.

It is an arithmetic number, because the mean of its divisors is an integer number (19286460).

Almost surely, 2^211805121 is an apocalyptic number.

It is an amenable number.

211805121 is a deficient number, since it is larger than the sum of its proper divisors (96778239).

211805121 is a wasteful number, since it uses less digits than its factorization.

211805121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10496.

The product of its (nonzero) digits is 160, while the sum is 21.

The square root of 211805121 is about 14553.5260675893. The cubic root of 211805121 is about 596.0904335921.

The spelling of 211805121 in words is "two hundred eleven million, eight hundred five thousand, one hundred twenty-one".