211121550 has 72 divisors (see below), whose sum is σ = 570599640. Its totient is φ = 55963200.

The previous prime is 211121513. The next prime is 211121557. The reversal of 211121550 is 55121112.

211121550 is a `hidden beast` number, since 2 + 1 + 112 + 1 + 550 = 666.

It is a super-3 number, since 3×211121550³ (a number of 26 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211121557) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 79240 + ... + 81860.

It is an arithmetic number, because the mean of its divisors is an integer number (7924995).

Almost surely, 2^211121550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 211121550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (285299820).

211121550 is an abundant number, since it is smaller than the sum of its proper divisors (359478090).

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

211121550 is a wasteful number, since it uses less digits than its factorization.

211121550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2818 (or 2810 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 18.

The square root of 211121550 is about 14530.0223674983. The cubic root of 211121550 is about 595.4484766992.

Adding to 211121550 its reverse (55121112), we get a palindrome (266242662).

The spelling of 211121550 in words is "two hundred eleven million, one hundred twenty-one thousand, five hundred fifty".