211221090 has 48 divisors (see below), whose sum is σ = 581483448. Its totient is φ = 53011968.

The previous prime is 211221077. The next prime is 211221091. The reversal of 211221090 is 90122112.

It can be written as a sum of positive squares in 4 ways, for example, as 209873169 + 1347921 = 14487^2 + 1161^2 .

It is a super-2 number, since 2×211221090² = 89228697721576200, which contains 22 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (211221091) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 67497 + ... + 70556.

Almost surely, 2^211221090 is an apocalyptic number.

211221090 is an abundant number, since it is smaller than the sum of its proper divisors (370262358).

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

211221090 is a wasteful number, since it uses less digits than its factorization.

211221090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138083 (or 138080 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 211221090 is about 14533.4472854860. The cubic root of 211221090 is about 595.5420430654.

The spelling of 211221090 in words is "two hundred eleven million, two hundred twenty-one thousand, ninety".