211221990 has 48 divisors (see below), whose sum is σ = 627632928. Its totient is φ = 48279168.

The previous prime is 211221979. The next prime is 211222019. The reversal of 211221990 is 99122112.

It is a super-3 number, since 3×211221990³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 167007 + ... + 168266.

It is an arithmetic number, because the mean of its divisors is an integer number (13075686).

Almost surely, 2^211221990 is an apocalyptic number.

211221990 is an abundant number, since it is smaller than the sum of its proper divisors (416410938).

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

211221990 is a wasteful number, since it uses less digits than its factorization.

211221990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 335293 (or 335290 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 211221990 is about 14533.4782485130. The cubic root of 211221990 is about 595.5428889201.

The spelling of 211221990 in words is "two hundred eleven million, two hundred twenty-one thousand, nine hundred ninety".