211221988 has 12 divisors (see below), whose sum is σ = 369815740. Its totient is φ = 105560352.

The previous prime is 211221979. The next prime is 211222019. The reversal of 211221988 is 889122112.

It can be written as a sum of positive squares in 2 ways, for example, as 133217764 + 78004224 = 11542^2 + 8832^2 .

It is a super-2 number, since 2×211221988² = 89229456429344288, which contains 22 as substring.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2343 + ... + 20686.

Almost surely, 2^211221988 is an apocalyptic number.

It is an amenable number.

211221988 is a deficient number, since it is larger than the sum of its proper divisors (158593752).

211221988 is a wasteful number, since it uses less digits than its factorization.

211221988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25326 (or 25324 counting only the distinct ones).

The product of its digits is 4608, while the sum is 34.

The square root of 211221988 is about 14533.4781797063. The cubic root of 211221988 is about 595.5428870404.

The spelling of 211221988 in words is "two hundred eleven million, two hundred twenty-one thousand, nine hundred eighty-eight".